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The Best Chains to Ever Buy

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The Best Chains to Ever Buy
What's the Millimeter MM Size of Your Diamond?

A lady comes into the jewelry store looking to upgrade her diamond engagement ring because it was “dull and didn’t sparkle”.

The appraisal she got with the ring said her diamond was a round brilliant cut, 1.00 carat, SI1 clarity, G color.

Not too bad really…!

So I start showing her better quality 1 carats and bigger (up to 1.25). All certified, round brilliant cut, VVS, VS, E-F color… Just outstanding stones.

Right away she notices one thing. Her 1.00 carat diamond looked really small when compared to them. Our 1.25 carat diamond didn’t just look a little bigger than hers did, ut it actually looked twice as big.

It didn’t make her happy

She started to get really curious about diamonds and started to compare her stone to the one carat solitaires we had in the showcase.

Her diamond looked visibly smaller than all of them. She started to panic thinking she got ripped off, “Mine was supposed to be a 1 carat!”, and that the jeweler must have lied about the weight and scammed her. To her it looked like a 3/4 carat diamond instead of a full carat.

I looked at her diamond appraisal, which was just a typed piece of paper on the jeweler’s letterhead. And of course… it’s not certified. The appraisal clearly stated that her diamond was in fact 1.01 carats. Hmmm, interesting.

I can tell the customer is about to have a nervous breakdown. She’s thinking maybe they switched her diamond during sizing, or that the jeweler lied about the diamond’s size during purchase. She was upset and scared, and it was up to me to calm the customer down.

So I measure her diamond:

I get the millimeter gauge (This is a diamond gauge that jewelers use to measure the width of diamonds and gemstones), and measure her 1.00 carat diamond. It comes up smaller than a normal 1.00 carat, of course.

The gauge reads 6.0 MM instead of 6.5 MM. But I can’t get a great reading of the entire diamond because it’s buried deep in the mounting. And if you can’t see the bottom of the diamond, you can’t truly measure it. Without seeing the culet (the point of the diamond), there’s no true way to measure the depth of the stone, which is needed for approximating carat weight.

The depth of the diamond, which on a good cut should be about 3.97 MM. This info isn’t listed on the appraisal either (But I already knew that). Usually only certified diamonds list that type of detailed information.

So what’s up?

I suspect a couple things are wrong with the cut of the diamond because the crown sits up high and it’s chunky. Plus the diamond’s girdle is extremely thick to very thick (wavy) all the way around. I would guess from these two indications, that her diamond is what they call a “deep stone (or a nail head)”.

I explain this to the customer. I tell her that the only way to truly get the carat weight of her diamond, other than approximating, is to have her stone physically removed from the mounting and weighed on a precision jeweler’s diamond scale. That’s the only way to be exact.

So what does the customer do?

She tells us to go ahead, remove it, and weigh it.

She wants the truth!

So we have the jewelers in the shop pull back a couple of prongs and out comes the diamond. And as suspected, the diamond is very thick and deep.

It is then put on our diamond scale and is weighed. We do this entire procedure in front of the customer just to make her feel at ease. The diamond turned out to be 1.01 carats on the dot!

The appraisal was correct.

Her diamond was just a tad bit over one full carat.


Nope, not really!

The valuable lesson to point out here is: all diamonds are not cut the same.

You really have to watch out for proportions and cut. It’s like 2 people that both weight 150 lbs. One person could be short and squat, while the other could be tall and skinny. Both could weight the same, but look entirely different.

You can’t tell carat weight by looks alone.

Her stone was very deep and the girdle was thick (a lower make stone often sold to keep the cost down). From the top down, her diamond looked like a much smaller diamond. Her MM was only 6.0 MM. This is why it’s so important to not forget about cut in the 4C’s. Cut makes a huge difference in appearance and beauty. Cut, depth and MM size can affect your diamond greatly.

You can also lose brilliance and sparkle too!

Cut is all that… For you could buy a diamond with great color, you could get an awesome clarity, but if that diamond is not cut right, if it’s too shallow or too deep, then that diamond will not only lose light and brilliance and sparkle, but it will also look different than all other 1 carats.

The customer ended up trading in her 1.01 carat mini-me diamond and was extremely happy with her upgrade (that looked twice as big). Her new 1.25 carat was simply stunning (And correctly cut and GIA certified too).

Now I’m not saying that the jeweler who sold her that smaller-looking diamond did anything wrong. They sold her the proper carat weight, color and clarity that she wanted. They just happened to hold back some crucial diamond information: CUT.

They ended up losing a customer

By not explaining to her that the stone was deep (hence the low price), and that it lost light and lacked sparkle, they ultimately lost a customer for life. They didn’t realize that by explaining to the customer that the reason the diamond was such a great deal was because of the poor cut. They actually hurt themselves. They could have talked her into not only a better diamond, but more than likely a bigger diamond as well.

She learned a valuable lesson and so should you. Color and clarity isn’t everything…

You must look at cut.

Cut does not mean ‘round‘ (that’s the shape!). Cut means the actual angles and proportions and depth and percentages and millimeter size.

Read more about diamond cut here. Study the diagrams. Become informed. Cut affects the life, light and beauty of a diamond more than any of the other 4 C’s.


The proper MM size for a 1.00 carat round diamond is 6.5 MM wide and 3.97 MM deep (Give or take a MM or two, there will always be a little leeway.)

Look at the Diamond’s girdle also. The girdle should be thin-medium in thickness and consistent all the way around the diamond’s edge.

Lastly… Buy certified!

Take the easy way when it comes to buying diamonds… Just buy a one carat GIA certified diamond instead.

Why GIA certified?

Because jewelers will normally only get a diamond certified by GIA if it’s worth it. Which means, chances are good that the diamond will have a good cut, good color and good clarity (look at the cut grades, you’ll want to see “excellent” or “very good” at the least). Now this is not always the case, but jewelers usually don’t certify crappy diamonds. (Again we’re talking GIA here, not IGI or EGL).

Learning about the cut and depth of a diamond will help you buy better looking diamonds.

Plus, it can also stop jewelers from selling you poorly cut stones that look small and lose light.

Inferior cuts of diamond may be cheaper, but you won’t be happy with the results.

Choose a great cut (“EXCELLENT” GRADES ALL THE WAY BABY), or get stuck with a bad stone…

It’s your choice.

Choose wisely.

Cheers! :)

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  1. NOBODY explained such things to young couples, or young men alone, shopping in the “chain” or “Mall stores” back in the 70’s. If you didn’t walk in the door already armed with such information – or as much as you could get back then – then you were at the mercy of the salesmen. And they weren’t about to part with any more information willingly than they had to, in order to make a sale. Besides, in their eyes, an educated customer was one they could not pull the wool over the eyes of, and therefore a “dangerous” customer. A little knowledge being a dangerous thing. If you wanted knowledge, then you usually had to find your way to the single-owner, big bucks, stores. This was where you could actually see loose stones, wrapped carefully in white tissue, and be encouraged to examine them with a loupe, so you could actually know what you’re getting for your money. This was about as close as you could get to seeing or purchasing great quality stones, not already mounted.

    And, back then, I wasn’t anywhere near as educated on diamonds, buying diamonds, judging diamonds, etc., as I became later on – after getting married, and learning more as I went along.

    In the meantime, I saw all kinds of old “appraisals” of diamonds, listing them as “Brilliants” or “Rounds” and “blue white,” “bright white,” or “almost white” and numerous terms for clarity, or none at all. And for fluorescence? “Fuhget aboudit” – No such a thing.

    All the stores had to do was print and make available in racks by their doors, and in the “Sunday salespapers,” bright, full color sales brochures, with highly magnified images of their merchandise that made rings look like huge donuts to attract the catalog collectors, like me.

    By comparison, I started noticing that different stores began carrying the exact same merchandise, down to the partial carat size stones, for the exact same prices. It didn’t make a bit of difference which store you went to, they were all getting to be the same.

    It took quite a while, with the blossoming of the GIA, and the idea that an educated, intelligent customer could be turned into a customer for life, by taking him/her into “your confidence” when you started sharing all those educated little details with them, about the secrets of diamonds, and the best way to buy them. The “old guard” salesfolk didn’t believe any of it though, and lost customers in the process. We are at a much better place now days. And thank goodness and the GIA for that.

    • Well said. TV certainly turned things around and opened people’s eyes. It definitely made a more educated customer with shows like 20/20. I’m happy for it. Makes my job easier. :) -Richard

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