It's Costco not Tiffany

Okay, this one is hilarious and should go on the top of the list of Ha-ha funnies.
In the 21st century, lives a woman who knows a lot about jewelry especially fine jewelry. You know the kind who looks at a diamond and can tell you the type of "Letter" it belongs to. Just so you know, I am on the opposite spectrum of this - I cannot make out if a glittery thing is a diamond or a cubic zirconium, I can only tell you that it shines and it looks nice.Besides, I really don't care for these expensive baubles and don't own any. Anyway, back to the story. Lady jewelry- know-it all is a very successful professional woman with many people reporting to her. One of them happen to be a pretty young single woman. As it often happens to PYT, she met her prince and got engaged. Also like all PYT, she was very excited and showed her ring around to one and all, saying it was from Tiffany's. Lady Jewelry-Know it all, saw it first.
She said "Congratulations it is lovely"
Then they went on to discuss the cut and quality of the rock.
Later, at the water cooler, the ring popped up in the conversation and people were saying things like " Did you see the rock on PYT's finger?"
Someone else said,"It's from Tiffany - lucky girl - must have cost him a bundle"
Lady Jewelry could not stop herself - her fine jewelry sense was seething with disdain"Waah!!" she said,"It is from Costco not Tiffany!"

All this over a piece of very old carbon.