SteamWorld Dig
14 Achievements
1,000
8-10h
Two Kinds of People
Complete the game with more than 20000 gold collected in total.
50
6.69%
How to unlock the Two Kinds of People achievement in SteamWorld Dig - Definitive Guide
Gems can be destroyed by falling rocks and magnetic crushers, though you'd have to really try for it to destroy 2,000 gold's worth. Similarly, you only need to collect, so spend what you need! Finding all secrets within caves will definitely help matters as well.
I did however go through all the doors and all 3 levels (as one should before meeting Vectron) =)
Going into the separate mines is also a good place to get gold since the secret areas in them usually carry very valuable materials like diamonds and emeralds.
(Missable)
Gold can be collected from mining the myriad of ore blocks in the various worlds of the mineshaft. There are far more than 20,000 gold worth of ores in the game, so this shouldn't be a problem. You can get it on your first playthrough to help you on your way to Fully Loaded, but it is one of the requirements for Master Prospector, so you can obtain it then if you want. This trophy is missable however, as you lose coins upon death. If you lose too many coins this way, you may have to play through the game again.
If you're having trouble getting this trophy, there is an upgrade in Vectron that allows you to see the location of minerals and orbs, thus making this trophy considerably easier. You can also expand the map via the pause menu if necessary.