Taken from the official World of Warcraft Forum are the current gem droprates from prospecting Ores. (updated Jan.2008)
Copper Ore:
Malachite: 50.0%
Tigerseye: 49.0%
Shadowgem: 9.7%
Tin Ore:
Moss agate: 38.4% (1-2)
Lesser Moonstone: 37.5% (1-2)
Shadowgem: 37.1% (1-2)
Jade: 3.6%
Citrine: 3.4%
Aquamarine: 3.2%
Iron Ore:
Jade: 31.9% (1-2)
Citrine: 31.3% (1-2)
Lesser Moonstone: 30.5% (1-2)
Aquamarine: 5.3%
Star Ruby: 5.1%
Mithril Ore:
Aquamarine: 31.3% (1-2)
Star ruby: 31% (1-2)
Citrine: 30.3% (1-2)
Blue Sapphire: 2.6%
Large opal: 2.6%
Huge emerald: 2.5%
Azerothian diamond: 2.4%
Thorium Ore:
Star Ruby: 29.4% (1-2)
Blue Sapphire: 16.9% (1-2)
Large Opal: 16.9% (1-2)
Huge Emerald: 16.6% (1-2)
Azerothian diamond: 16.6% (1-2)
Deep Peridot: 1.6%
Flame Spessarite: 1.5%
Golden Draenite 1.5%
Shadow Draenite: 1.5%
Azure Moonstone: 1.4%
Blood Garnet: 1.3%
Fel Iron Ore:
Deep Peridot: 16.6% (1-2)
Blood Garnet: 16.3% (1-2)
Azure Moonstone 16.2% (1-2)
Shadow Draenite: 16.2% (1-2)
Golden Draenite: 16.1% (1-2)
Flame Spessarite: 15.7% (1-2)
Living Ruby: 1%
Nightseye: 0.9%
Dawnstone: 0.9%
Talasite: 0.9%
Noble Topaz: 0.9%
Star of Elune: 0.9%
Adamantite Ore:
Adamantite Powder: 100%
Golden Draenite: 19.0% (1-2)
Shadow Draenite: 19.0% (1-2)
Azur Moonstone: 18.9% (1.2)
Deep Peridot: 18.9% (1-2)
Flame Spessarite: 18.8% (1-2)
Blood Garnet: 18.7% (1-2)
Dawnstone: 2.7%
Talasite: 2.7%
Living Ruby: 2.7%
Noble Topaz: 2.6%
Star of Elune: 2.6%
Nightseye: 2.5%
the only problem i would see with this is why would bc gems prospect out of pre-bc ore? there is no thorium anywhere in the outlands so it seems odd that blizzard would allow the outlands gems to be prospected from azeroth ore. also, blizz you suck for the blue gem prospecting drop rate. i hardly ever get good gems from prospecting adamantite 🙁
Well the prospecting has incresed quite a lot since 2.1 and there ar eplenty of blues now. The rates above have not really been updrated on the forum – yet.