Does Costco sell real diamonds?

I'm curious, does Costco, the renowned retailer known for offering a wide range of products at affordable prices, actually sell real diamonds? I've heard of them carrying a variety of jewelry, but I'm not sure if their diamond selection is genuine or if they only stock simulated stones. It would be great to know if shoppers can find authentic diamonds at Costco, and if so, what kind of quality and pricing they can expect. I'm also wondering if there are any specific conditions or certifications that Costco requires for their diamond inventory to ensure that they're selling the real deal.