You don’t see many twelve-sided diamonds around. They’re hard to cut, which is why the cut requires a hard stone, which is why the only twelve-sided gems are diamonds. A twelve needs a big stone or a really good cutter, and both of those are limited commodities. The fact is that an eight will get almost as much money, so the twelves just aren’t done any more.

I’ve looked into this. I’m not a gemologist or artisan, but I’ve been considering the Bethany diamond for almost 20 years. That’s what I call it. Because Bethany was the first woman to refuse the stone in its 93-year history.

Bethany is my best friend. We met in college, 31 years ago, and we haven’t stopped talking since. She fell in love with Tom in 1979 when we were 29 and trying to manage a failing bookstore. He proposed marriage a year later, but she resisted. They’re still together. He tried to give her the diamond when he first proposed. He’s offered it regularly since.

The diamond is only 2.7 carats but it’s a beauty. I mean, 2.7 carats is a good size, but it’s a small stone for the amount of attention it’s gotten, from Tom and Bethany and me, not to mention its previous owners. It’s a guilt diamond, but it has just about been reformed now.

I know quite a bit about its history. It was found in a Brazilian river gravel mine shortly after the turn of the century. Most diamonds are octahedral; the rare rhombic dodecahedrons almost all came from Brazil instead of Africa or India. Fyvush Lubunsky, the cutter, was also the original seller; he told Tom’s great-grandfather Herschel.

According to Herschel’s notes, the stone was cut in 1905. He says Lubunsky didn’t know how best to treat the diamond until the cleaving of the 971-carat Excelsior in Amsterdam in 1904. And the cut Bethany diamond’s size wasn’t officially determined until 1913, when the U.S. adopted the metric carat (200 milligrams) as its standard; by then the diamond was on the breast of its second owner.

Herschel Goldman bought the stone in 1906, had it set in a gold necklace, and draped it around the swan-like neck of his mistress Sylvie. He was then 40 and she was 25; from the way he wrote about her it’s clear he was smitten and would do just about anything to keep her. Except leave his wife Esther. She was a good Jewish woman who had given him three sons; in 1906 divorce simply wasn’t an option. So Herschel bought the diamond for Sylvie.

She left him anyway, five years later. She broke his horny heart. She gave him back the diamond. But hurt Hersch wore his broken heart on his sleeve and Esther became suspicious. In a token of guilty placation, on their 25th wedding anniversary, Herschel presented the diamond to his wife.

Esther wore the stone from 1911 to 1920. She had it reset into a brooch in 1913, and she fastened the gem on her prow-like bodice for all important occasions. Herschel commented in his notes about growing to hate the look of the diamond staring at him like an unblinking eye from that momentous bosom.