---
title: "Magic sizes: meaning in gemology"
description: "Magic sizes are round-number weights, such as half a carat or one carat. They sell for more because of demand, not looks."
url: https://digitalgemology.com/learn/glossary/magic-sizes
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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> Site index: https://digitalgemology.com/llms.txt

[Glossary](https://digitalgemology.com/learn/glossary) · Four Cs

# Magic sizes

Also called magic weights, round-number weights

Magic sizes are round-number weights, such as half a carat or one carat. They sell for more because of demand, not looks.

## In more detail

In our simulator, a 0.99 ct T73 is 0.02 mm narrower than a 1.00 ct. Nobody can see that, but the price below the line is usually much lower. GIA's cut booklet notes that cutters can paint or dig out the half facets to save weight. One reason is to reach one carat.

## Related terms

- [Carat weight](https://digitalgemology.com/learn/glossary/carat-weight): Carat weight is the weight of a gemstone. One carat is 200 milligrams, a fifth of a gram, and it has 100 points.
- [Painting and digging](https://digitalgemology.com/learn/glossary/painting-and-digging): Painting and digging out are small tilts of the half facets along the girdle. Cutters use them to save weight.
- [Weight ratio](https://digitalgemology.com/learn/glossary/weight-ratio): Weight ratio is the part of GIA's cut grade that compares a diamond's weight with its diameter. A stone can carry too much or too little weight for its width.

## Learn more

- [Carat weight vs size: why a 2 ct diamond isn't twice as big](https://digitalgemology.com/learn/four-cs/carat-weight-vs-size)
- [Star length and lower half length in a round brilliant](https://digitalgemology.com/learn/diamond-anatomy/star-length-and-lower-half-length)

[All 328 terms](https://digitalgemology.com/learn/glossary)