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.