This is definitely the way I want to go. Cremated and then having my carbons processed under intense heat and pressure into an artificial diamond, and then set into jewelry. Hopefully then I could possess the bearer should they fail a will save, safe within my eternal phylactery. You even get to customize the size, shape and number of diamonds up to your total cremated mass, so if you had the cash you could be made into a crown, necklace, pendant, bracelet, etc... all bejeweled by YOU!
I wonder if Beryl's clergy will offer competitive pricing?
I think I'd want to be a purple amethyst hue set into silver etched with Celtic designs. Either that or molded wholly into a crystal skull with red tinted gems for eyes. That would be awesome.
Or better yet, the Aurin curling snake pendant design from Neverending Story with red emerald eyes. Just imagine, you could have it engraved with your own cryptic message, like "The Bearer of the Heartstone will claim power over all the World and those who walk upon it" in old Latin. People would come across your remains and think they found a piece of the bloody Necronomicon or something!