Fellow Selling Sunset lovers will remember the furore that Romaine’s purchase of a moissanite, rather than diamond, ring for then-fiancée Mary Bonnet caused.
In fact, diamonds only became the “go-to” engagement ring choice in the early-to-mid-1900s, partly due to a De Beers marketing campaign in the 1940s.
Nonetheless, the stone has reached such a coveted status since that fakes (by which I mean non-diamond materials posing as the real thing, rather than lab-grown diamonds which are identical to the mined kinds) abound.
So how can you tell what you’re looking at if you’re in doubt?
A ‘fog test’ can be helpful
Jewellery appraiser Kevin Zavian told PBS’s Antiques Roadshow that one way to test a suspicious stone is to simply breathe on it.
“The cz [cubic zirconia, a synthesized material that looks a lot like diamonds] tends to hold on to the moisture” from your breath for longer than diamonds do, keeping them fogged up.
Meanwhile, The Diamond Pro, a site run by diamond industry expert and consumer educator Mike Fried, agrees: “If the fog dissipates right away, the diamond is real. If it takes several seconds for the fog to disperse, it is likely a fake diamond.”
The Cape Town Diamond Museum specifies that “if it stays fogged for three to four seconds chances are that you’re looking at a fake.”
However, moissanite can fool those running the fog test, as it, too, gets rid of fog quickly.
You can also buy diamond testers relatively inexpensively, Zavian shared. But for him, the “best and quickest way is, I use a loupe” or a tiny magnifying glass to check for giveaway blunt edges on the stone’s facing.
Any other methods?
You can draw a line with a marker on a piece of paper, Zavian said. While a diamond will obscure the mark, it should be crystal-clear through a fake stone.
Other methods, like seeing whether your rock looks blue under UV light, can be effective but only work for about a third of diamonds, the Cape Town Diamond Museum says.
Meanwhile dropping your “diamond” into a glass of water to see if it sinks can reveal a genuine stone, but it’s “not conclusive” as other non-diamond substances are dense too.
If you really want to go all-out, you can send your rock to a gem certification lab.
“Usually, it’s not the unscrupulous jewellery dealer [offering fake diamonds] ― it’s the unscrupulous boyfriend,” Zavian joked.