---
title: "Curved striae: meaning in gemology"
description: "Curved striae are curved growth lines or color bands in a flame-fusion synthetic. Natural corundum grows with straight, angular zoning instead."
url: https://digitalgemology.com/learn/glossary/curved-striae
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Clarity characteristics

# Curved striae

Also called curved growth lines, curved color banding

Curved striae are curved growth lines or color bands in a flame-fusion synthetic. Natural corundum grows with straight, angular zoning instead.

## In more detail

With round or elongated gas bubbles, curved striae point to a flame-fusion stone. They can be hard to see in pale stones. Immersion or short-wave ultraviolet light helps a gemologist see them.

## Related terms

- [Flame fusion](https://digitalgemology.com/learn/glossary/flame-fusion): Flame fusion grows synthetic crystals by dropping fine powder through a very hot flame. The melted drops build up a crystal on a pedestal below.
- [Synthetic gemstone](https://digitalgemology.com/learn/glossary/synthetic-gemstone): A synthetic gemstone is made in a laboratory and has essentially the same chemistry and properties as the natural gem. A synthetic ruby is ruby, made by people.
- [Color zoning](https://digitalgemology.com/learn/glossary/color-zoning): Color zoning is uneven color in a gem: bands or patches of deeper and paler color.
- [Inclusion](https://digitalgemology.com/learn/glossary/inclusion): An inclusion is a clarity characteristic inside a diamond, or one that reaches the surface from inside.

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