The short answer: pigeon blood describes the most prized ruby colour, a vivid, slightly bluish red, while glass filled rubies are lower quality stones that have had fractures filled to improve their look and need careful handling. Know which you are buying, and ask for a report.
Ruby has its own vocabulary. Two terms often seen are pigeon blood and glass filled, and they sit at opposite ends of the market.
Pigeon blood rubies
Pigeon blood is a term for a rich, saturated red with a hint of blue, historically linked to fine stones from Burma. Today it is used in the trade for top colour, and some laboratories use it in their reports for stones that meet certain criteria. Not every stone sold as pigeon blood qualifies, so ask what the report states, and we can help you read it.
Glass filled rubies
Glass filled rubies are lower quality stones with fractures that have been filled with a glass like material to improve clarity and appearance. They can look attractive and are usually lower in price.
How to spot filling
Filling is best identified by a gemmological laboratory, but there are clues. Under magnification, filled fractures can show tiny gas bubbles or a flash of colour as the stone is tilted, and the surface may show areas of different lustre. A very low price for a large, clean looking ruby is also a warning sign. If in doubt, ask for a report that covers treatment.
Why it matters
- The filling is less durable than the stone and can be damaged by heat, acids and some jewellery cleaning.
- Repairs can be affected by filled stones.
- The stone should be sold as glass filled, and not as a natural untreated ruby.
Comparison
| Fine ruby | Glass filled ruby | |
|---|---|---|
| Colour | Rich, vivid red | Varies, often improved |
| Durability | High | Needs careful treatment |
| Price | Higher | Lower |
| Care | Standard | Avoid heat, acids and harsh cleaning |
Heated rubies
Heating is a common and widely accepted treatment for ruby, and it is different from glass filling. Heat can improve colour and clarity, and the result is stable in everyday wear. A report should say whether a stone has been heated. Glass filling is a separate and more significant treatment, and it affects care and value.
Ruby colour in different light
Ruby can look quite different in daylight and under warm indoor light. Some stones glow strongly under daylight, which contains ultraviolet light, while others look darker or browner indoors. We show you stones on video in several kinds of light, so you choose a ruby that looks beautiful wherever you wear it.
How to buy well
- Ask for an independent report.
- Check for treatment, including filling.
- See the stone in natural light.
- Choose a setting that suits the stone.
Our approach
We describe every stone honestly, including any treatment, and we tell you if a stone is not suited to daily wear. Lab grown rubies are an option if you want a clean, vivid red, and we label them clearly.
See best settings for ruby, heated vs unheated sapphires and the hardness chart, and browse diamonds for accent stones. Nothing is made until you approve the design in writing, and our standard making time is 5 to 6 weeks, which can vary with your location and how busy we are. Pieces start from £600.
Frequently asked questions
Does pigeon blood mean top quality? It describes colour, so check the report and the stone.
Are glass filled rubies bad? They are fine if sold honestly, but they need care.
Can a filled ruby be repaired? Repairs can be affected, so tell your jeweller.
Is heating the same as filling? No, heating is a different and more widely accepted treatment.
Can I order a ruby ring from overseas? Yes, by video consultation, with insured, tracked FedEx delivery.