From what I can see, here is no gemstone so reviled and despised as Adventurine. The only thing conceivably more valuable than a small, broken piece of Adventurine is having no Adventurine at all. Because... Adventurine Shards - Rare! - worth 40 Gold Pieces Small Adventurine - Rare! - worth 40 Gold Pieces Adventurine Trinket - Uncommon - worth 10 Gold Pieces Large Adventurine - Uncommon - worth 10 Gold Pieces Shiny Adventurine - Uncommon - worth 10 Gold Pieces Adventurine Gem - Common - worth 2 Gold Pieces So broken pieces and small pieces are much rarer and more valuable than large pieces, shiny pieces, trinkets made from the stuff, or gem quality pieces. Apparently it's very difficult to break, kind of a nuisance in large pieces, and annoyingly shiny. I picture giant slabs of the stuff all over the place with no easy way to break them up and get rid of them, their facets glittering tackily in the sunlight. Ugh. I only wish this extended into Epic and Legendary Treasures. Perhaps the Epic can be "Adventurine Dust," and Legendary can be "Contains Absolutely No Adventurine." That last one would be awesome.
Well, you could buy all that adventurine fresh picked, but it's so much more luxurious and tasty if you pay someone else to shuck them for you first. I imagine it's final legendary form will be a Jar of Adventurine Butter TM.
The other gems are similar: all the Shards except Amethyst and Diamond are Rare. The Legendary could be called Homeopathic Adventurine.
True, shards in general do appear to be rare. Adventurine seems to be the only variety of gem to come in such a variety of sizes and flavors, though. Ooh, how about "I Can't Believe It's Not Adventurine!"