Several of my pieces were bought in estate jewelry sections of jewelry stores and so far so good....I've heard of this as well and I'm in the Caribbean. I love opals and have a few pieces and plan on getting more so that shows what I think about it.
I've heard people say they refuse to buy pawned jewelry because of fear of bad luck. I thought so for a while until I got this great pair of sapphire and diamond earrings for less than 1/4 of the price for similar stuff in regular stores. Since then, I've bought several amazing pieces and haven't had any bad luck. I also think it's a great way of getting unique pieces.