How to Identify Purple Gemstones
Last updated: October 2026
22 of the 132 gem species in our database occur in purple. 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 purple 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 22.
| Transparency | Purple species |
|---|---|
| Transparent You can clearly see through it | 17 |
| Translucent Light passes through but you cannot see clearly | 12 |
| Opaque No light passes through, even at thin edges | 8 |
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 purple species shows, largest first:
| Left | Transparency · lustre | Candidates |
|---|---|---|
| 16 | Transparent · vitreous Glass-like shine | Almandine Garnet, Amethyst, Ametrine, Color-Change Garnet, Color-Change Sapphire, Fluorite, Hackmanite, Iolite, Kunzite, Rhodolite Garnet, Sapphire, Scapolite, Spinel, Synthetic Color-Change Corundum, Taaffeite, Tanzanite |
| 12 | Translucent · vitreous Glass-like shine | Almandine Garnet, Amethyst, Fluorite, Hackmanite, Iolite, Jadeite, Sapphire, Scapolite, Spinel, Star Garnet, Star Sapphire, Sugilite |
| 8 | Opaque · vitreous Glass-like shine | Charoite, Hackmanite, Jadeite, Sapphire, Spinel, Star Garnet, Star Sapphire, Sugilite |
| 3 | Opaque · waxy Dull, wax-like sheen | Hackmanite, Jadeite, Sugilite |
| 3 | Opaque · silky Fine, directional sheen from parallel fiber structures | Charoite, Star Garnet, Star Sapphire |
| 3 | Translucent · waxy Dull, wax-like sheen | Hackmanite, Jadeite, Sugilite |
| 2 | Translucent · silky Fine, directional sheen from parallel fiber structures | Star Garnet, Star Sapphire |
| 1 | Translucent · resinous Warm, amber-like glow | Scapolite |
| 1 | Transparent · adamantine Brilliant, diamond-like sparkle | Cubic Zirconia |
| 1 | Transparent · resinous Warm, amber-like glow | Scapolite |
| 1 | Transparent · waxy Dull, wax-like sheen | Hackmanite |
Where your eyes stop
If your stone is genuinely purple, transparent, with a vitreous lustre, it is still one of 16 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 purple 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 purple 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 purple gemstone by its colour?
No. 22 of the 132 species in the Loupewise database occur in purple, so colour tells you where to look, not what the stone is. Adding transparency and lustre — both free to observe — still leaves up to 16 candidates in a single group (transparent, vitreous). Separating those takes a measurement such as specific gravity or refractive index.
What is the cheapest way to narrow down a purple 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.