I guess the most people that are selling high-level-gems do just not know, how much gold they invested to craft this gem. They just know, that they paid 500k for the last step so 10 mio sounds more than enough ...
Don't forget that those gems, once made, almost never leave the game. Even those who quit might remember how much they paid for it (20m) and look to turn it into some $. If people don't buy the gems at 16m, then if you happen to own one, your only choice is to sell cheaper.
Now in addition to amethysts and topaz, I've seen emerald prices under pressure in the US AH recently. They fluctuate between 10m and 17m. For this one I'm less sure about the reason. It might be random ripples in the market, but I think there must be more to it. Either high end players quitting, or people trying to buy gold through emeralds to get a cheaper rate.
Note that I don't believe in the duping theory. Why? Because I would dupe the gem that sells for 20m (ruby) instead of one that sells for 10m. Even a duper should have this minimal amount of intelligence.
I personally don't believe in dupes because item can only be created server-side.
So then here is my question...if your leaving the game, why bother selling your gems?
Cause (a) he can sell the gold for $$ or ( if he ever decides to play again it's nice to have some gold lying around
Bingo. I'm selling all my gear on the RMAH (gems included). Think of it as cashing out.
I am still debating on how much gold I should leave on my account in case I ever come back (D3 is a good game but it just gets boring farming the same content over and over again... Plvl 50 is enough for me for now).
So what do all of you think about the price of square gems increasing after 1.0.5? (square gems will no longer drop)
Right now, square amethysts are going for ~69 gold each, and square topazes are at ~61 gold each (US AH).
Due to them becoming more scarce after the patch, even if they go up to 200 gold each, buying them now would result in 300%+ profit. It is possible that the price on amethysts will skyrocket due to people wanting that extra +life% in helms for ubers.
Would you say buying a crapload of square gems is super risky? Because I've bought over 16k squares so far.