Ruby Identification With Lasers, Magnets, and X-rays

Andy Kong
8 min readMar 12, 2022
The eBay ruby

Kings, queens, and rich people everywhere agree: rubies look great. Their clarity and red color make them wonderful, shiny jewelry pieces, and I find them beautiful. But if you’re buying one, there are many similar red, clear gemstones which are much cheaper for the seller to pawn off as ruby. How can we know that we aren’t getting ripped off when we buy a “ruby” online?


Our story begins with me, your humble author, developing a vague desire to make a ring with a big ruby inset. Not only would it look great, I also thought it’d be a cool DIY gift.

The first problem came from trying to acquire a big ruby. Every gemstone store online had huge price tags on their rubies that I couldn’t even begin to afford, starting at $2000–$20,000 per carat (a carat is 0.2 grams). The stone starts being visible around 0.1 carats, already 200 dollars, and I realized that natural ruby is a great deal more expensive than I thought.

Affordable eBay rubies

In my desperation, I turned to the only place I could always count on to find a great deal: eBay. Here, I found many stores selling ruby for the great low price of ~$0.50/carat. Perfect for my price range. I found a nice cut I liked and hit purchase on a 10 carat ruby for $20.

Seeds of doubt

When it arrived, the ruby glittered a deep red, and its 10 carats gave the stone a lot of volume. It looked beautiful, and I felt more than happy just to look into its red depths.

But when I showed my friend, he had the complete opposite reaction. Instead of being awestruck, he asked skeptical questions like “How much did it cost?” and “How do you know it’s real?”, which I hadn’t considered at all. I began to wonder if my ruby dealer had ripped me off to make a couple more dollars…

Trust, but verify

At its core, my ruby’s authenticity doesn’t matter — it does a great job of being a shiny, clear red stone even if it isn’t a crystal made of aluminum oxide. But it really got to me because it reminded me how little we know about many parts…

Andy Kong

Cultivating curiosity. More on my site: