I invested nearly 297,840 gp in 40 diamonds nearly 5 days ago. It was almost the lowest the market for them had been in 180 days, only the next day being ~160 gp lower then when I bought mine.
I invested in them because the highest they had been in 180 days was 12k, that'd be a 5k profit each, money I could definitely use. And good news so far, uncut diamonds price has gone up to 7,795 gp and I hope it goes up further.
Wish me luck in my first little practice run of investing.