Watch Parts Scale Buying Guide: Accuracy, Capacity and Calibration

Posted by AWS Team on Sep 15th 2026

Choosing a scale for watch parts comes down to three technical questions:

How much measurement detail do you need?

How much total weight must the scale support?

How will the scale be calibrated and checked?

These questions correspond to:

accuracy and measurement performance, capacity, and calibration.

Watchmaking makes this particularly important because the objects being weighed can range from extremely lightweight movement components to complete watches.

A watchmaker, repair shop, collector or parts dealer might need to weigh:

Screws
Springs
Pins
Washers
Watch hands
Jewels
Gears
Crowns
Stems
Movement components
Complete movements
Cases
Case backs
Clasps
Buckles
Bracelets
Complete watches
Batches of replacement parts

A scale optimized for a tiny screw may not have enough capacity for a complete watch.

A scale designed for a complete watch may not display enough detail for a tiny movement component.

The goal is therefore not to find the scale with:

the most decimal places.

The goal is to find the scale whose:

readability + measurement performance + capacity + calibration requirements

match the watch parts you actually weigh.

For many general watchmaking applications:

500g × 0.01g

provides a practical balance.

For extremely lightweight individual components:

0.001g readability

may be useful.

For professionals working across both extremes:

two scales may be better than one.

Quick Watch Parts Scale Buying Guide

Watch Part	Readability to Consider	Capacity to Consider
Tiny screw	0.001g	20–100g
Spring	0.001g	20–100g
Pin	0.001g	20–100g
Watch hand	0.001g	20–100g
Jewel	0.001g	20–100g
Small gear	0.001g	20–100g
Crown	0.001–0.01g	50–500g
Stem	0.001–0.01g	50–500g
Movement component	0.001–0.01g	50–500g
Complete movement	0.01g	100–500g
Watch case	0.01g	200–500g+
Bracelet	0.01g	200–500g+
Complete watch	0.01g	500g+
Parts batch	0.01–0.1g	Depends on batch

These are practical starting points rather than universal measurement requirements.

Accuracy, Capacity and Calibration: What Is the Difference?

Before comparing scales, separate these three concepts.

Accuracy and Measurement Performance

This concerns how well the weighing system produces useful measurements within its specified operating conditions.

Important factors can include:

Readability
Repeatability
Linearity
Calibration
Minimum usable load
Environmental stability

Capacity

Capacity is:

the maximum physical load the scale is designed to support.

Calibration

Calibration uses:

an appropriate known reference mass and specified procedure

to evaluate or adjust the weighing system.

These concepts interact, but:

they are not interchangeable.

Readability Is Not the Same as Accuracy

This is one of the most important rules in precision weighing.

Suppose a scale displays:

1.347g.

That tells you the display has:

0.001g readability.

It does not automatically prove:

±0.001g accuracy.

Likewise:

a 0.01g scale

does not automatically guarantee:

every measurement is accurate within ±0.01g.

Readability tells you:

the smallest increment shown on the display.

AWS explains this distinction further in its guide to what 500g × 0.01g means on a digital scale.

What Does 0.001g Readability Mean?

A scale with:

0.001g readability

changes its display in increments of:

one-thousandth of a gram.

That equals:

1 milligram.

Examples:

0.023g

0.024g

0.025g

This level of readability can be useful for:

very lightweight watch parts.

Which Watch Parts May Benefit From 0.001g?

Possible examples include:

Tiny screws
Springs
Watch hands
Pins
Small washers
Tiny gears
Jewels
Lightweight movement components

AWS's Best Milligram Scales guide compares 0.001g models designed for fine measurement applications.

Do All Watch Parts Need 0.001g?

No.

Suppose you weigh:

Complete movement = 31.42g

Case = 68.35g

Bracelet = 96.48g

Complete watch = 181.76g

Milligram readability may provide:

more displayed detail than the application requires.

Meanwhile, the low capacity of many milligram scales becomes:

a major limitation.

What Does 0.01g Readability Mean?

A 0.01g scale changes its display in:

one-hundredth-of-a-gram increments.

Examples:

2.35g

31.47g

168.29g

For general watchmaking:

this is often a highly practical level of readability.

Which Watch Parts Work Well With 0.01g?

Depending on the task:

Crowns
Stems
Movement assemblies
Complete movements
Cases
Case backs
Clasps
Bracelets
Complete watches
Parts batches

can often be weighed effectively using:

0.01g readability.

0.001g vs. 0.01g for Watch Parts

Consider:

Scale A

50g × 0.001g

Scale B

500g × 0.01g

Scale A provides:

10× finer displayed increments.

Scale B provides:

10× greater maximum capacity.

Neither is automatically:

better.

The correct choice depends on:

the object.

Example: Tiny Watch Screw

Suppose a screw weighs approximately:

0.038g.

0.001g scale

can display:

0.038g.

0.01g scale

cannot show the same level of detail.

For this task:

milligram readability may be valuable.

Example: Complete Watch

Suppose a watch weighs:

185.42g.

50g × 0.001g scale

cannot weigh it at all.

500g × 0.01g scale

can.

For this task:

capacity matters more than the additional decimal place.

More Decimal Places Do Not Automatically Mean Better Measurement

A scale showing:

12.347g

looks more precise than:

12.35g.

But the number of digits alone does not tell you:

Accuracy
Repeatability
Stability
Calibration condition
Minimum usable load

Do not buy a watch-parts scale according to:

display digits alone.

Repeatability Matters

Repeatability concerns whether repeated measurements of the same object under similar conditions produce:

consistent results.

Suppose you weigh the same crown five times:

2.37g
2.37g
2.37g
2.37g
2.37g

That demonstrates:

consistent displayed measurements under those conditions.

Now suppose the readings are:

2.31g
2.39g
2.34g
2.42g
2.30g

The additional digits are less useful if:

the measurement is unstable.

How to Check Repeatability

A simple practical test:

Place the watch part on the scale.
Allow the display to stabilize.
Record the measurement.
Remove the part.
Confirm the display returns to zero.
Replace the same part.
Record the result.
Repeat several times.

Look for:

consistent readings.

Minimum Usable Load Matters

Maximum capacity receives most of the attention.

But precision weighing also has:

a lower end.

A scale that displays:

0.001g

does not automatically mean every object weighing:

0.001g

can be measured meaningfully.

Where available, review manufacturer specifications related to:

Minimum load
Accuracy
Repeatability

This is particularly important for:

extremely lightweight watch components.

Capacity: The Second Major Buying Factor

After determining how much measurement detail you need:

calculate capacity.

Capacity is:

the maximum physical load supported by the scale.

A scale might be:

20g × 0.001g

50g × 0.001g

100g × 0.001g

500g × 0.01g

2,000g × 0.1g

Each configuration serves:

a different working range.

Capacity Must Include Everything on the Scale

This is critical.

Use:

watch part + tray + container + holder = total physical load.

Suppose:

Movement = 37g

Tray = 18g

Total:

55g.

A 50g scale is:

not sufficient.

Tare Does Not Restore Capacity

Suppose:

scale capacity = 50g

tray = 15g.

Place the tray on the scale.

Display:

15.000g.

Press:

TARE.

Display:

0.000g.

You do not now have:

another 50g

of physical capacity.

The tray is still applying:

15g

of load.

Approximate remaining physical capacity:

35g.

Why This Matters With Milligram Scales

Low-capacity milligram scales may have:

20g

or:

50g

maximum capacities.

A tray that seems lightweight can consume:

a meaningful percentage

of the available range.

Leave Capacity Headroom

Avoid selecting a scale where your normal load sits:

right at maximum capacity.

Suppose:

complete watch = 460g

holder = 25g

total = 485g.

500g scale

technically has enough nominal capacity,

but provides:

very little headroom.

A higher-capacity model may be more practical.

Capacity for Tiny Watch Parts

For:

Screws
Springs
Hands
Pins
Jewels

20–100g capacity may be enough.

If these are your primary objects:

fine readability may matter more than:

high capacity.

Capacity for Crowns and Stems

Crowns and stems generally provide:

more flexibility.

Depending on the workflow:

50–500g capacity

can work well.

Capacity for Complete Movements

Complete movements can be substantially heavier than:

individual movement components.

For this task:

100–500g capacity

provides more flexibility.

Capacity for Watch Cases

Cases can become:

relatively heavy.

When weighing:

case + case back + holder,

low-capacity milligram scales can become impractical.

Capacity for Bracelets

Metal bracelets can weigh:

significantly more than tiny watch parts.

Prioritize:

adequate capacity

and:

platform size.

Capacity for Complete Watches

For many complete watches:

500g capacity

provides a practical range.

But do not assume:

every watch fits this range.

Weigh or estimate:

your actual heaviest watch.

Capacity for Parts Inventory

A batch of:

200 screws

may weigh considerably more than:

one screw.

If your workflow involves:

batch inventory,

calculate:

the complete batch weight.

Platform Size and Capacity Work Together

A scale can have:

enough capacity

while still having:

an inconvenient platform.

Suppose:

capacity = 500g

watch = 180g.

The capacity is sufficient.

But if:

the watch and bracelet cannot sit securely on the platform,

the scale may still be inconvenient.

Complete Load Must Be Supported by the Scale

Do not allow:

part of a bracelet

to rest on:

the workbench.

If part of the object is supported by another surface:

the scale is not receiving the entire physical load.

General-Purpose Watch Parts Capacity

For users who want:

one scale

for a broad range of watch parts,

500g provides useful flexibility.

The AWS SC501g Precision Digital Pocket Scale combines:

500g capacity

with:

0.01g readability.

It also provides:

3.9 × 3.7-inch platform
Stainless-steel weighing surface
Tare
Two expansion trays
Multiple weighing units
Battery operation

For many general watchmaking tasks:

this combination balances capacity and readability well.

When 500g Is More Useful Than 50g

Suppose your workflow includes:

Screw = 0.08g

Crown = 2.4g

Movement = 32g

Case = 65g

Bracelet = 105g

Complete watch = 195g

50g × 0.001g

scale can weigh:

the small components.

It cannot weigh:

the case, bracelet or complete watch.

500g × 0.01g

scale covers:

far more of the overall working range.

When 50g × 0.001g Is More Useful

Now suppose your work focuses almost entirely on:

Screws
Springs
Pins
Jewels
Tiny gears

and the largest complete load is:

10g.

In this case:

500g capacity may provide little practical benefit.

Finer:

0.001g readability

may be more valuable.

Calibration: The Third Major Buying Factor

Precision weighing depends partly on:

proper calibration.

Calibration relates the weighing system to:

an appropriate known reference.

It should be performed according to:

the manufacturer's procedure.

Calibration Requirements Are Model-Specific

Do not assume:

all scales calibrate using the same mass.

One scale may require:

20g.

Another may require:

500g.

Always check:

the exact model.

SC501g Calibration

The SC501g specifies:

500g calibration weight.

The calibration weight is:

not included.

This is important to know before:

purchasing the scale.

GEMINI Calibration

AWS's milligram-scale range includes models with:

different calibration arrangements.

For example:

the GEMINI-50 includes:

a 20g calibration weight.

That can make:

initial setup and routine calibration

more convenient.

Use the Correct Calibration Mass

Do not improvise.

If the manufacturer specifies:

20g,

use the appropriate:

20g calibration mass.

If it specifies:

500g,

use the appropriate:

500g mass.

Do Not Use Coins for Calibration

A coin is:

an everyday object.

It is not a substitute for:

an appropriate calibration weight.

Do not use:

Coins
Watch batteries
Screws
Cases
Bracelets
Jewelry
Tools

as improvised calibration standards.

Calibration Is Not the Same as Tare

These functions are completely different.

Calibration

relates the scale's response to:

a known reference mass.

Tare

subtracts the displayed weight of:

a container or tray.

Calibration Is Not the Same as Zeroing

Zeroing establishes:

the zero reference.

Calibration evaluates or adjusts:

the scale's response using a known mass.

Calibration Does Not Fix Environmental Problems

Suppose a properly calibrated scale sits:

directly under an air-conditioning vent.

The display may still:

fluctuate.

Likewise, calibration cannot eliminate:

Vibration
Air movement
Static
Unstable surfaces
Poor placement

Calibration is important,

but it is not:

the only requirement for reliable weighing.

Use a Stable Surface

Place the scale on:

a firm, level surface.

Avoid:

Soft watch mats under the scale
Flexible tables
Uneven workbenches
Moving surfaces

The watch itself may be handled over:

a protective mat,

but the scale needs:

stable support.

Avoid Vibration

Watch repair workspaces may contain:

Polishers
Tools
Machinery
Speakers

that introduce vibration.

This can become especially noticeable with:

0.001g readability.

Avoid Direct Airflow

Milligram-level measurements can be affected by:

air movement.

Avoid placing the scale directly beneath:

Fans
HVAC vents
Open windows

Consider Draft Protection

For extremely lightweight watch parts:

draft protection can help stabilize:

milligram measurements.

This is particularly relevant when working with:

Springs
Hands
Tiny screws
Lightweight movement components

Consider Static Electricity

Very lightweight components may also be influenced by:

static effects.

If a tiny part produces unusual fluctuations:

check the environment.

Consider Temperature Stability

Precision weighing generally benefits from:

stable operating conditions.

Avoid immediately performing fine measurements after:

large temperature changes.

Accuracy Depends on the Whole Weighing Process

A common mistake is assuming:

the scale alone determines the result.

The complete measurement system includes:

scale + calibration + surface + environment + handling + object placement.

NIST's guidance on balance and scale calibration and uncertainties emphasizes calibration procedures, appropriate reference standards and potential sources of measurement uncertainty.

Center the Load

Whenever practical:

place the object near the intended weighing area.

Avoid:

awkward off-center loading.

For complete watches:

use a suitable platform or tray.

Use a Tray for Tiny Watch Parts

A tray can help contain:

Screws
Springs
Pins
Washers
Crowns
Gears

Procedure:

Place empty tray on scale.
Allow display to stabilize.
Press tare.
Confirm zero.
Add watch part.
Allow measurement to stabilize.
Record result.

Remember:

the tray still counts toward maximum physical capacity.

Handling Tiny Watch Components

Tweezers can be useful for:

small components.

They help reduce:

Dropping
Rolling
Excessive handling

Some milligram-scale packages include:

tweezers and weighing accessories.

Choosing Between 20g, 50g and 100g Milligram Scales

If you require:

0.001g readability,

capacity becomes the next decision.

20g × 0.001g

Best suited to:

extremely lightweight work.

50g × 0.001g

Provides:

more practical headroom

for trays and small groups of components.

100g × 0.001g

Useful when:

milligram readability is needed

but 20–50g capacity is too restrictive.

GEMINI-20 vs. GEMINI-50 for Watch Parts

Both models provide:

0.001g readability.

The primary capacity difference is:

GEMINI-20 = 20g

GEMINI-50 = 50g.

AWS's GEMINI-20 vs. GEMINI-50 comparison explains the capacity difference while both retain milligram readability.

For watch parts:

the 50g version can provide greater flexibility for:

trays and groups of components.

When to Choose 500g × 0.01g

Choose this configuration when:

your workflow includes:

Complete movements
Cases
Bracelets
Complete watches
Larger parts
Parts batches

and:

0.01g provides sufficient displayed detail.

When to Choose 50g × 0.001g

Choose this configuration when:

your workflow focuses on:

Screws
Springs
Hands
Pins
Jewels
Small gears
Tiny movement components

and:

milligram-level readability matters.

When to Choose Two Scales

Some watchmakers need both:

extremely fine readability

and:

substantial capacity.

Example working range:

Tiny screw = 0.035g

Spring = 0.080g

Crown = 1.75g

Movement = 31.60g

Case = 64.80g

Bracelet = 102.50g

Complete watch = 188.40g

No single compact scale necessarily provides the ideal specification for:

every task.

A two-scale setup can solve this.

Precision Scale 1

50–100g × 0.001g

for:

tiny components.

Precision Scale 2

500g × 0.01g

for:

larger parts and complete watches.

Why Two Scales Can Be Better Than One

The goal is not:

owning more equipment.

The goal is:

matching measurement range to the task.

A low-capacity milligram scale provides:

fine readability.

A 500g precision scale provides:

greater working capacity.

Together:

they cover a much broader watchmaking range.

Accuracy for Watch Screws

Tiny screws can benefit from:

0.001g readability

when comparing individual components.

But remember:

readability is not an automatic accuracy guarantee.

Accuracy for Watch Springs

Lightweight springs may require:

milligram readability.

Environmental stability becomes particularly important.

Accuracy for Watch Hands

Watch hands are extremely lightweight.

Use:

a stable environment

and:

appropriate tray.

Accuracy for Watch Gears

Small gears may benefit from:

0.001g.

Larger gears may be adequately measured at:

0.01g.

Accuracy for Crowns

For many crowns:

0.01g provides useful measurement detail.

If extremely fine comparison is required:

0.001g may be considered.

Accuracy for Complete Movements

For complete movements:

0.01g generally provides:

considerable measurement detail.

Capacity and platform size become:

more important.

Accuracy for Watch Cases

For cases:

prioritize:

Adequate capacity
Stable platform
Suitable physical size

Milligram readability is generally less important than it is for:

tiny movement parts.

Accuracy for Bracelets

Bracelets can be:

large and relatively heavy.

500g × 0.01g

configuration can be much more practical than:

a 20–50g milligram scale.

Accuracy for Complete Watches

For complete watches:

0.01g readability generally provides:

fine displayed detail.

Prioritize:

capacity and correct positioning.

Weight Does Not Identify a Watch Part

A screw weighing:

0.084g

cannot automatically be identified according to:

weight alone.

Weight cannot independently establish:

Manufacturer
Reference
Compatibility
Material
Authenticity

Use weight as:

one measurement characteristic.

Weight Does Not Authenticate a Watch

Suppose a genuine reference is commonly associated with:

a particular weight range.

A matching measurement still does not independently prove:

authenticity.

Counterfeit or modified watches can potentially approximate:

expected mass.

Authentication requires:

additional evidence.

Weight Does Not Determine Metal Composition

Mass alone cannot prove that:

a case is gold

or:

a bracelet is stainless steel.

Material identification requires:

additional information or testing.

Weight Does Not Determine Value

Watch value can depend on:

Manufacturer
Model
Reference
Rarity
Condition
Originality
Provenance
Materials
Market demand

Weight is:

one data point.

Commercial Use Requires Additional Consideration

If a scale is used for:

internal repair, inventory, comparison or hobby measurements,

the requirements differ from:

commercial transactions determined directly by weight.

The current 2026 edition of NIST Handbook 44 contains specifications, tolerances and technical requirements used by weights-and-measures authorities for commercial weighing and measuring equipment.

Do not assume:

a consumer precision scale is automatically legal for trade.

Watch Parts Scale Comparison

Configuration	Main Advantage	Main Limitation	Strong Use
20g × 0.001g	Very fine readability	Very low capacity	Tiny individual parts
50g × 0.001g	Fine readability + more room	Still limited capacity	Screws, springs, gears
100g × 0.001g	Fine readability + higher capacity	Specialized range	Small component work
500g × 0.01g	Excellent versatility	Less detail for ultra-light parts	General watchmaking
2kg × 0.1g	High capacity	Coarser readability	Large batches

Accuracy vs. Capacity: Which Matters More?

Neither universally matters more.

For:

a 0.03g screw,

readability and fine measurement performance matter greatly.

For:

a 250g watch,

capacity matters first.

If the object exceeds:

maximum capacity,

the scale is:

the wrong scale

regardless of its readability.

Calibration vs. Readability: Which Matters More?

They solve different problems.

Readability determines:

the display increment.

Calibration relates:

the scale's measurement response to an appropriate reference.

You need:

both appropriate readability and proper calibration.

Calibration vs. Repeatability

A scale can be calibrated and still produce inconsistent readings if:

the environment is unstable.

Repeatability should therefore be:

observed and considered separately.

Watch Parts Scale Buying Checklist

Before buying, ask:

What watch parts will I weigh?
What is my lightest component?
What is my heaviest component?
What is my heaviest complete watch?
Will I weigh parts individually?
Will I weigh parts in batches?
Do I need 0.001g readability?
Would 0.01g be sufficient?
What accuracy specifications are available?
What repeatability information is available?
What is the minimum usable load?
What is maximum capacity?
What does my weighing tray weigh?
What is my maximum complete physical load?
Have I left capacity headroom?
What is the platform size?
Will the object sit securely?
Does the scale have tare?
Do I understand that tare does not restore capacity?
What calibration mass is required?
Is the calibration weight included?
Is calibration straightforward?
Do I have the correct reference mass?
Is my workbench stable?
Is the scale level?
Is vibration present?
Is direct airflow present?
Could static affect lightweight parts?
Is temperature stable?
Would draft protection help?
Do I need a tray?
Do I need tweezers?
Do I need piece counting?
Are the components sufficiently consistent for piece counting?
Do I need multiple units?
Do I need battery operation?
Do I need portability?
Will I weigh complete watches?
Would 500g × 0.01g cover most of my work?
Do I also need a 0.001g scale?
Would a two-scale setup be better?
Am I confusing readability with accuracy?
Am I relying on weight for authentication?
Will the scale be used for regulated commercial transactions?

Frequently Asked Questions

What is the best scale accuracy for watch parts?

There is no universal specification.

For many general watch parts:

0.01g readability

is practical.

For extremely lightweight individual components:

0.001g readability

may be useful.

Is 0.001g necessary for watch repair?

Not for most complete watches or larger components.

It becomes more useful for:

tiny screws, springs, hands, gears and movement components.

What does 0.001g mean?

It means:

the scale displays increments of:

one milligram.

Does 0.001g mean ±0.001g accuracy?

No.

That figure describes:

readability.

Accuracy and repeatability are:

separate considerations.

Is 0.01g enough for watch parts?

For many:

Crowns
Movements
Cases
Bracelets
Complete watches

yes.

What capacity scale should I use for watch parts?

For general watchmaking:

500g

is a versatile starting capacity.

For tiny components:

20–100g milligram scales may be sufficient.

Is 500g enough for a complete watch?

For many watches:

yes.

But determine:

the actual heaviest object in your collection or workflow.

Does a tray count toward scale capacity?

Yes.

Everything physically supported by the weighing mechanism counts toward:

total load.

Does tare give me more capacity?

No.

Tare changes:

the displayed result.

It does not increase:

physical maximum capacity.

What is the best general-purpose watch parts scale?

500g × 0.01g

precision scale is a strong general-purpose configuration.

What is the best scale for tiny watch parts?

Consider:

50–100g × 0.001g

when milligram-level readability is genuinely required.

How do I calibrate a watch parts scale?

Use:

the manufacturer's specified calibration procedure

and:

appropriate calibration mass.

Can I use a coin to calibrate my scale?

Do not use random household objects as substitutes for:

proper calibration masses.

How often should I calibrate?

Follow the manufacturer's instructions and your own measurement requirements.

Calibration may be appropriate after:

moving the scale

or when:

measurement performance needs to be checked.

Why does my milligram scale fluctuate?

Possible contributors include:

Vibration
Airflow
Static
Unstable surface
Temperature changes
Object movement

Does platform size affect accuracy?

The object should be:

securely supported

and properly positioned.

Do not allow part of a watch or bracelet to rest on:

another surface.

Can I weigh watch screws in a tray?

Yes.

Use:

tare

to remove the tray from the displayed measurement.

Can a scale count watch screws?

Some scales provide:

piece counting.

This works best with:

components having consistent individual weights.

Can a scale authenticate a Rolex or luxury watch?

No.

Weight alone cannot independently establish:

authenticity.

Can weight identify a genuine watch movement?

No.

It can be:

one measurement

but cannot independently establish:

identity or authenticity.

Can weight determine whether a watch is gold?

No.

Mass alone cannot prove:

material composition.

Should a watchmaker own two scales?

If the workflow ranges from:

extremely lightweight movement components

to:

complete watches,

two scales can provide better coverage.

Final Verdict: Watch Parts Scale Buying Guide

The right watch-parts scale is determined by:

accuracy and measurement performance + capacity + calibration.

Start by identifying:

the lightest component that matters to your work.

Then identify:

the heaviest complete physical load.

Remember:

complete load includes:

watch part + tray + container or holder.

For tiny:

Screws
Springs
Pins
Hands
Jewels
Gears
Movement components

consider:

0.001g readability

when milligram-level displayed increments are genuinely required.

For broader watchmaking involving:

Crowns
Complete movements
Cases
Bracelets
Complete watches
Parts batches

500g × 0.01g

provides an especially practical balance of:

capacity and readability.

The AWS SC501g is a strong general-purpose configuration with:

500g capacity
0.01g readability
3.9 × 3.7-inch platform
Tare
Expansion trays
Multiple units
Battery operation

For tiny component work:

50–100g × 0.001g

milligram scale can provide finer displayed increments.

Calibration should always follow:

the procedure for the exact model.

Use:

the specified calibration mass.

Do not substitute:

coins, watch parts or household objects.

And remember:

calibration does not eliminate problems caused by:

vibration, airflow, static or unstable surfaces.

For a watchmaker working across an extreme weight range, a strong setup is:

0.001g milligram scale for tiny components + 500g × 0.01g precision scale for movements, cases, bracelets and complete watches.

The most important rule is:

do not buy the scale with the most decimal places—buy the scale whose measurement performance, capacity and calibration requirements match the watch parts you actually weigh.