Jewelry prices are ridiculous.
I work at a pawn and car audio shop, so I see all kinds of jewelry. (and idiots)
We can put a $600 price tag on a ring that appraises for $2000 and it will sit in the case for a year. Then a jeweler will show up, buy it for $500, put it in their case for $1800, and sell it!!!
And IMO, diamonds are worthless (unless 1ct+). Hell, if you come in the shop w/ a nice ring w/ a cluster of 5pt stones and weighs 5.0 dtw, we will only buy it based on gold weight. You can literally hit that ring w/ a hammer and I'll give you the same amount. On top of that, is you walk in w/ a chain broken into 4 pieces and it weighs 10 dtw...i'll give you twice what I would on the ring.