So you wanna buy her a diamond. The hard part is over. You found your soul mate. Now, you want to give her something that will last forever, just like your love for each other. Or maybe it’s for your husband, grandmother, mistress, favourite high school teacher, or butcher.

But how do you choose the right ring? What makes one diamond nicer than another? I had no idea what I was doing when I went diamond shopping in downtown Montreal just before Christmas.

All I knew was it felt right, and my girlfriend was probably going to go into a coma when she opened her Christmas present. I didn’t even know how much to spend.

My first attempt didn’t work out too great. I walked into a small jewelry store on Ste-Catherine Street and said, “I want to buy a diamond ring.” The clerk looked me over and, without losing eye-contact, reached back to hit a button on the wall. A door opened and a big serious-looking fellow stepped out, eyeing me suspiciously.

My good vibes were disappearing fast. The clerk pulled out what looked like a suitcase and opened it up. Inside were dozens of diamond rings of all shapes and sizes. I figure he had at least $100,000 worth in there. So you can see why they had lots of security. I looked at a few rings, but nothing really caught my eye. They all looked pretty much the same to me.

I decided to do a little research on the internet, which is where I struck “gold.” There are lots of sites about choosing diamonds. They also tell you how not to get ripped off. I was quickly learning that there are a lot of profiteers in the “love business.”

One good tip I got off the internet was that you should find a jeweler you trust. This is where fate took over. I looked in the Yellow Pages under jewelry wholesalers, and the first place to catch my eye was the Gemmological Laboratory of Canada, located downtown on de Maisonneuve Blvd.

As soon as I talked to the owner, Yves Godbout, I knew he was my man. Not only is he a 25-year industry veteran who appraises diamonds for retailers and sells them himself, but he also studied karate for more than 20 years and used to have his own martial arts magazine.

Godbout took the time to introduce me to the interesting world of the diamond business. You can tell he loves his job. His eyes sparkled as he talked about these twinkling little stones while letting me explore them under a microscope.

The biggest mistake people make is thinking size is all that matters. A lot of people walk into a jewelry store with the idea of buying the biggest diamond they can afford. Unfortunately, many jewelers take advantage of this by selling low-quality diamonds that happen to be big.

A diamond’s weight is measured in carats. There are 142 carats in an ounce. Each carat is further divided into 100 points. Ninety-nine percent of diamond owners have one that’s smaller than a carat.

The first thing to know is that two diamonds with the same carat weight can have a very different value. A one-carat diamond can cost anywhere from $16,000 for a top-quality stone – that’s 8,000 times the value of gold – to as little as $2,800.

Carat weight is just one of the “four Cs” that decide a diamond’s value. The other “Cs” are clarity, colour and cut. These are the factors that determine how “brilliant” a diamond is – how it sparkles and catches the light.

Clarity refers to the diamond’s “purity” – whether it has flaws, or “inclusions.” Most diamonds on the market have little cracks, spots or feathers in them, and a good jeweler will point them out with a microscope. The bigger the flaws, the duller a diamond will look.

Colour is also important. The whiter the diamond, the higher the value. Many retailers, including big department stores, only sell diamonds with very poor colour ratings. If you look closely, you will notice they look a little yellow or grey.

Finally, there is cut. A diamond has to be shaped by an experienced master draftsman to very precise dimensions for it to break down the light and redirect it to show off its brilliance and clarity.

How can you tell if you should trust a diamond retailer? Godbout says beware of anyone selling “top light browns.” These are yellowish diamonds that are usually sold with a big discount. If a jeweler has a 50-percent-off sale all year long, there’s a good chance they’re not selling a quality product.

Ideally, a jeweler should show you the stone before it’s mounted in a ring, so you can see it under a microscope and compare several stones. “If they say it’s a VS (only very slightly flawed) and there is a big inclusion in the middle, you know there’s something wrong,” said Godbout.

“It’s like buying a good wine. The main thing is to see what you’re buying.”

A few other tips:

– Don’t feel pressured to buy a diamond just to prove you love someone. Your love is what’s important.

– Platinum bands are better than gold. Gold wears out and you can lose the stone. Also, my brother, a chemical engineer, tells me gold is very slightly radioactive.

– Make sure the ring holds the diamond firmly in place. You might want to get six prongs instead of the usual four.

– Get it insured.

And by the way, she said yes.

The Gemmological Laboratory of Canada can be reached at (514) 843-5059. On the web check and