Spready Table, Old Mine, and Ideal Cut Diamonds – Parts of a Diamond


Simple diagram of diamond from GIA

Parts of a Diamond. Courtesy of GIA

The day I started caring about the parts of a diamond was many moons ago. But I like the unusual so my ears perked up the first time I heard my diamond dealer say “She has a ‘spready table.” Yes, just like cars we refer to diamonds as she.

My immediate response was “what?”

I took a closer look and noticed that it looked like a carat, but weighed .85ct. That’s less than a carat, 85/100ths of a carat to be exact. It also lacked sparkle. “What is a ‘spready table’?” I asked. It didn’t sound like diamond techno-speak to me.

The Spready Diamond

spready diamond

Bigger Than Normal Table

“Well you know the table is the flat part on top. When it is wider than normal, that often suggests it’s cut less deeply. It looks bigger on top, but sparkles less”

“I’m thinking spready table is bad,” I responded.

Profile pic of a diamond in tweezers.

The Proportion From the Table to the Culet is Shallow, Meaning it Sparkles Less.

“Well, can we define bad? If someone wants a diamond that looks like a carat and they don’t care about much else and they don’t want to pay for a carat it’s an answer to a prayer.”

“So it’s bad.”

“Yeah it’s bad. When you go out wide in your cut choices and don’t cut deeply enough, it throws off the proportions. The consequence is that light doesn’t refract (refraction is the light return from inside the gem as opposed to reflection which is light bouncing off the surface) the way it’s supposed to.”

This was my wake-up call to pay more attention to cut angles on a gem. I thought I’d share my story with you so learning the parts of your gem would have more purpose.

The Old Mine Cut, A Classic

gia old mine cut diamond diagram

Early on diamonds were cut with small tables and what they called windows on the bottom.

They thought light came in from the bottom to help light the diamond. Some diamonds were cut at the mine heads and had very interesting non-symmetrical faceting.

Eventually the technology was invented that measured light return (refraction) from an old-mine cut diamond. New cuts like the a modern brilliant, cut with no window on the bottom and a larger table on top were invented. It had a much great ability to refract light that the older cut styles. That was followed by the “ideal cut” with ideal proportions for light return.

Ideal Cut, Brought to us by Technology

Why aren’t all modern brilliants ideal cut? Diamond cutters want to cut the largest, heaviest diamond they can since diamonds are sold by weight.

Cutting each rough, round diamond into the ideal proportions isn’t realistic for all diamonds. They need to be cut based on where the inclusions lie.

Diamond cutters cut for the diamond in front of them. Many near ideal cut diamonds are gorgeous. Look at the diamond in front of you. When I first saw that spready table round diamond, I knew there was something off with it. It lacked life. I’ve also seen weird, off-ideal cuts done by a good diamond cutter that somehow sparkled anyway and looked beautiful.

Does Your Ideal Diamond Have to Be Ideal Cut?

GIA Diamond Anatomy

More Details About the Parts of a Diamond. Courtesy of GIA

Does that diamond you’re considering sparkle? Does it speak to you? That’s the most important consideration. Math doesn’t beat sparkle. I’ve seen amazing sparkle from an old mine cut diamond.

The GIA, Gemological Institute of America the leader in diamond grading doesn’t actually grade for an Ideal Cut, because it limits their grading criteria. Here’s an interesting page explaining the cut grade details they take into account when cut grading.

If you know the basic diamond angles and know how to use a loupe to magnify the diamond you’re looking at, you’ve got a good start on diamond selection. Just watch out for those spready table diamonds.

Your Personal Jeweler,

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About Calla Gold

Calla Gold is a Personal Jeweler and Author who takes pride in working with clients one-on-one to integrate their personal sense of style and taste into custom designed jewelry and repaired jewelry pieces.   Unlike typical Santa Barbara jewelry businesses, Calla Gold has no brick-and-mortar location. Calla Gold comes to you, bringing you the jewelry collection you want to see and collaborating with you to create unique custom jewelry. Calla also works with at-a-distance clients.

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SUNAR Jewels
SUNAR Jewels
4 years ago

Amazing Information about the shape and size of an ideal Diamond cut, shape, and size. Sometimes it amazes me that people should know all these pieces of information and should be aware of the current scenario where people are making fool out of others and selling them less worthy Diamonds. Appreciate it.