Carat measures weight; millimeters measure dimensions. A generic range can teach why equal-weight diamonds may face up differently, but the applicable report's length, width, and depth govern the individual stone.

A non-operative carat-to-millimeter teaching worksheet that separates diamond weight from report dimensions and shows why shape and proportions prevent one exact universal conversion.

What this guide covers

Name the diamond shape, cutting style, weight source, and whether a current report is available.
Keep carat, length, width, depth, ratio, and mounting state as distinct evidence fields.
Use the worksheet only to prepare questions, then confirm the exact stone and report connection elsewhere.

Inputs for a bounded comparison

The worksheet has no universal conversion table and must not invent report measurements.

Shape and cutting style, stated carat weight, source, report laboratory, report number, and report date
Recorded length, width, and depth in millimeters; ratio where relevant; loose or mounted state
Applicable cut fields, proportions, girdle, and comments without turning one number into a grade
Open identity, custody, condition, setting, price, availability, and seller-policy checks

Separate weight from visible spread

1 — Confirm the weight evidence
Record carat as weight and keep the source and report context attached.
2 — Read all three dimensions
Compare length, width, and depth with shape and proportions instead of converting weight to one diameter.
3 — Return to the exact report
Use a generic example only as education; preserve the item's recorded measurements and unresolved identity checks.

The result keeps unlike measures separate

Carat

Working result: Recorded weight and evidence source
Boundary: Not visible-size or value shorthand

Millimeters

Working result: Length, width, and depth from the applicable record
Boundary: Not guaranteed from carat alone

Individual stone

Working result: Report connection and open verification questions
Boundary: No identity, price, or availability conclusion

There is no exact universal carat conversion

Scope and disclosure · evidence version 2026-07-19
This local page does not accept inputs, calculate a diameter, verify a report, inspect a diamond, identify a stone, assess cut, predict appearance, price or value an item, retrieve inventory, reserve a stone, save a comparison, or recommend a purchase. Exact report measurements remain controlling evidence.

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