---
title: "Lead-glass filling: meaning in gemology"
description: "Lead-glass filling is a treatment that fills fissures and cavities in corundum, mostly ruby, with high-lead glass to hide them."
url: https://digitalgemology.com/learn/glossary/lead-glass-filling
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Treatments and origin

# Lead-glass filling

Also called glass-filled ruby, lead glass-filled ruby

Lead-glass filling is a treatment that fills fissures and cavities in corundum, mostly ruby, with high-lead glass to hide them.

## In more detail

It usually applies to low-quality stones. Colored flashes in the fissures can give it away. The glass is unstable to heat and to some chemicals; even lemon juice can change it. Clean these stones with a damp cloth only.

## On a grading report

Indications of heating, glass-filled fissures (and cavities), extent minor (F1), moderate (F2) or significant (F3). Badly fractured rough held together by glass is a manufactured product.

## Related terms

- [Manufactured product](https://digitalgemology.com/learn/glossary/manufactured-product): A manufactured product is a gem held together by glass or resin. It is made from badly fractured rough, or from many small pieces bound into one.
- [Clarity enhancement](https://digitalgemology.com/learn/glossary/clarity-enhancement): Clarity enhancement is filling surface-reaching fissures with a filler such as oil, resin, wax or glass, so they show less.
- [Ruby](https://digitalgemology.com/learn/glossary/ruby): Ruby is the red variety of the mineral corundum. Chromium causes its red color.
- [Stability](https://digitalgemology.com/learn/glossary/stability): Stability is a gem's resistance to damage from heat, light and chemicals.
- [Disclosure](https://digitalgemology.com/learn/glossary/disclosure): Disclosure is telling the buyer, before the sale, that a gem is treated, laboratory-grown or an imitation.

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