These bags only hold ingredients for Jewelcrafting, but are larger than the average general bag. Only 1 gem bag may fill a slot in a bank at any time.
“Gem bags are special bags that can store minerals and gems. The Gem Pouch is a 20-slot gem bag...Gem bag
“Bag of JewelsItem Level 65Binds when equipped24 Slot Gem BagSell Price: 3 This item can be...Bag of Jewels
“This item is created with Tailoring (515): [Pattern: Luxurious Silk Gem Bag]. Patch changes...Luxurious Silk Gem Bag