Finding Gemstones?

[Grobble]

I'm trying to do the Gemhunter credo and I keep getting quests to 'Mine a gemstone'
Once I get the improved chance I'm sure it will be easier, but what do I do until then? I've found some before and marked on my map where they were but I'm not finding any more in that area.
How am I supposed to find them other than extremely rare mining loot?

[Sevenless]

Gemstones have invisible nodes. When you find a gemstone, you know you've at least touched one of these nodes. Each node tends to have a couple different gem types in it. Only real way to find them is to prospect tunnel (tunnel in straight lines looking for ore, not rustroot prospecting) and marking down any time you find one.

Gemhunter is a pain if you don't have a wealth of mapped out nodes to make it easier. Good luck O7