Perhaps it's an unusual color or unique cut/shape. Something about a stone that says "look at me!" and you've just got to have it! We have a few of those on hand and just thought we'd share . .
Clockwise from top left:
Teal Tourmaline / 3.94ct / TU15-5485
Rose de France Amethyst / 10.46 cttw / AM2-5682
Yellow Sapphire / 1.06ct / SA6-5627
Rose Quartz / 7.74ct / RQ-5683
Blue Sapphire / 1.09ct / SA9-5623
Peridot / 5.01ct / PE3.5-5685