Nope.
Quite the opposite, in fact.
My question is: who are you hearing this from? My guess would be jewelers here in the states. My wife had to take some of her pieces in to be cleaned [the tanzanite and caribbean topaz pieces] and the inevitable conversation started: "these are beautiful, where'd you get them, we can try to match prices if you're looking to expand your collection..." and when they heard we got it in Cozumel [tanzanites came from Diamonds International, topaz from Rachat], they were surprised and offended that they were real and that they could not, in fact, come anywhere close to matching prices, and spent the rest of the time running down what had just been described as "beautiful". One of the excuses used is that tanzanite from the Caribbean are really amethysts.
Last year I got my mother a mother's ring on St Tom; she had to have it resized. Four and a half total carats split nearly evenly between peridot, amethyst and sapphire. It was a "beautiful" $1500 ring [more than 3x what I paid for it] until he learned where it came from, and then he was surprised that the stones were real.
Desperately seeking 10th cruise for the free laundry.