I think these are the died mineral "sillimanite", same with the emerald and sapphire ones.
These are nice earrings, but i think it's just the died mineral "fibrolite" also known as "sillimanite", same with the emeralds and sapphire ones.  I like the look of these earrings and also have the emerald and sapphire ones that are nice also for the price, but I emailed the seller and asked if they were real emeralds, rubies and sapphires and all they would say was they were "natural".  So I looked on the internet and it appears the cheap emeralds, rubies and sapphires from India are just the mineral "fibrolite/sillimanite" that they dye red, green, and blue, to create low cost imitation rubies, emeralds and sapphires.  I actually like the look of them, and for $15 they are probably worth it, just know that although they are "natural", they probably are not "real" rubies, emeralds and sapphires.
Rating: 3 stars