Just a random question:
Are chinese lab diamonds with IGI certification considered legit?

Got it sir.

Another question:
For a diamond size of <0.5carat, what's the highest specs one can go before it starts getting indistinguishable from the higher specs, with naked eye?

From what I have gathered so far, the sweet spot is G/H, VS2, 3EX, No BGM. The difference in price is not that much in the middle, but rise exponentially towards the high specs end.

Thus, thought of knowing this before getting influenced by jewellery stores