How to Identify Blue and Violet Gemstones
Last updated: October 2026
48 of the 132 gem species in our database occur in blue or violet. Colour tells you where to look; it cannot tell you what the stone is. Two more observations cost nothing — how much light passes through it, and how its surface shines. Below is exactly how far those two get you, counted over every blue or violet species we hold, and where you need an instrument to go further.
Step 1 · How much light passes through it
Hold the stone up to a light. A species recorded in more than one state is counted in each, so these add up to more than 48.
| Transparency | Blue and Violet species |
|---|---|
| Transparent You can clearly see through it | 30 |
| Translucent Light passes through but you cannot see clearly | 27 |
| Opaque No light passes through, even at thin edges | 22 |
Step 2 · How its surface shines
Tilt a flat polished face toward the light and judge the shine. Every combination of the two observations that any blue or violet species shows, largest first:
Where your eyes stop
If your stone is genuinely blue or violet, translucent, with a vitreous lustre, it is still one of 25 species. No amount of looking separates those reliably, because they differ in properties you cannot see: density, refractive index, optic character. A measurement does.
The cheapest useful one is often not the refractometer. Our gem testing kit comparison ran all 132 species through the identification engine to rank inexpensive instruments by how much each eliminates. If you have a refractive index reading, the blue or violet section of the RI-by-colour chart lists every candidate above sorted by it, and the confusion pairs reference gives the test that separates each commonly confused pair.
The app asks these same three questions. Transparency and lustre remove species; colour only moves blue or violet species to the top, because colour shifts with lighting and treatment and a wrong call should not throw out the right answer. Then it shows which test would eliminate the most of what is left. It needs observations or measurements; it cannot identify a gem from a photo.
Open the appFrequently Asked Questions
Can you identify a blue or violet gemstone by its colour?
No. 48 of the 132 species in the Loupewise database occur in blue or violet, so colour tells you where to look, not what the stone is. Adding transparency and lustre — both free to observe — still leaves up to 25 candidates in a single group (translucent, vitreous). Separating those takes a measurement such as specific gravity or refractive index.
What is the cheapest way to narrow down a blue or violet gemstone further?
A measured property. Specific gravity can be taken with a kitchen-scale setup, and a refractometer reading is the sharpest single cut. Our gem testing kit article ranks the inexpensive instruments by how many species each one eliminates across the whole database.