Agates come in a wide variety of natural colors brown red lilac pink yellow as well as black gray and white but as it is quite a porous gemstone it does take dye quite well so come brightly colored or even colored gems may well have been treated in this way. Find many great new used options and get the best deals for large blue agate polished tumbled rock mineral specimen crystal gemstone 65 8g at the best online prices at ebay. 39 00 shipping.