The stone, of one piece of which it was wrought, was such as I had never seen before. At the base it was of a full green, the colour of emerald without, of course, its gleam. It was not by any means dull, however, either in colour or substance, and was of infinite hardness and fineness of texture. The surface was almost that of a jewel. The colour grew lighter as it rose, with gradation so fine as to be imperceptible, changing to a fine yellow almost of the colour of “mandarin” china. It was quite unlike anything I had ever seen, and did not resemble any stone or gem that I knew.
Here’s a peculiar treasure: a beautiful stone of rare appearance. It has absolutely no magical qualities. What do the PCs do with it? Well, if they give it to a sculptor, they will be able to commission one small statue of surpassing quality and loveliness – that sculptor’s master work.
What will they do with the stone? Will a PC commission something personally meaningful? Will they give it to a patron NPC to curry favor? Will they commission something stupid? or will they let it sit unclaimed on someone’s character sheet?
I have a feeling that a lot of groups will take such a stone as a challenge to come up with something cool, and that will increase their investment in the game world.