where can i find current retail pricing 4 gemstones like amethyst,citrines, tanzinites and etc?

im getting into the gemstone bussiness and i pick up some awesome stones at realy cheap prices. but i dont know the current market prices to sell them at.

If you do not know the current market prices, how are you so sure you’re getting the gemstones for cheap?

3.97ct Amethyst Sterling Silver Heart Ring