Isadoras antique jewelry


Why It Matters and Why It Doesn’t

I'd like to take a moment to put the “4 C’s” diamond grading scale into context, because so often I see people ignore their own instincts about a stone in favor of a technical chart.

The Four C's is a way of grading diamonds set up in the 1950's by the G.I.A. (The Gemological Institute of America). The Four C's stand for color, clarity, cut and carat. And a gemologist's collective understanding of these Four C's is how he puts a monetary worth on a stone. And from a monetary standpoint, it is very important that a reputable gemologist has determined these four characteristics and priced the stone based on his assessment because diamonds have a very technical worth. But aside from assuring a fair price, the Four C’s, as a determinant in picking your stone, should not influence your personal attachment to a stone.

Below is an analysis the Four C’s. How an appraiser uses them to grade a stone and why they matter and why they don’t.


Color defines how white the stone is. The color scale ranges from a D (colorless) to Z (faint yellow). A stone darker than Z is classified as a colored stone and is not color graded in the same fashion. Monetarily a D stone has the greatest value and a Z stone the lowest.

vintage diamond engagement rings, antique wedding rings Different Color Diamond Rings

Having said that, just because a D stone has a greater monetary value does not mean it the prettiest stone or the stone you will love the most. If you like a little warmth in your stones, you may prefer diamonds with an O color grade or lower, stones often referred to as 'cape diamonds' in the antique jewelry business. The majority of antique stones will have a color grade of G to K.


Clarity defines how clear a stone is. Diamonds, like any object in nature, are prone to flaws, or inclusions. These may be bits of carbon in the stone that look like tiny black specks or feathering, which looks like very fine white lines. These are all natural, but the fewer of these natural inclusions in the stone, the greater the monetary worth. If there are no inclusions, the stone is graded FL or flawless. Clarity ranges from FL (flawless) to I3 (imperfect).

A FL stone is far more expensive than an I3 stone. However as long as the ring is a SI or above, the inclusions will not be visible to the naked eye and will require magnification to be visible. Also if you fall in love with a ring that does fall into the I1 category, you need not automatically dismiss it. Sometimes the inclusion will be obvious, but often a good jeweler will hide the flaw under a prong so it is not visible. And it may be a way to get a big stone for a low price.


Cut defines how well the jeweler has faceted the stone. And the rating can range from “Excellent” to “Poor”. This is the rating that is the least applicable when rating an antique stone. The qualifications for “cut” were determined in the 1950’s, well after the majority of antique and vintage stones were cut, when different trends and styles were in place. The majority of well-cut antique stones will fall under “good” because their aim was different than stones today.


Carat (or Weight) is the metric unit of weight used in the gem stone industry to describe how much a gemstone weighs. Carat is equal to 1/5th of a gram. This is the least arbitrary of the determinations. The larger a stone is, the exponentially larger the price. This is because a larger stone is exponentially more rare.

vintage diamond engagement ring Vintage Diamond Engagement Ring

A note about why carat prices can differ, even with similar statistics. With a diamond you are paying for the diamond you see and the diamond you don’t see. This is not a bad thing. When cutting a stone to create a beautifully faceted diamond, a jeweler has to loose a certain percentage of the stone. This is dependent on the stone he begins with, the design he chooses to cut and how exact he wants to be with the proportions. This is why a brilliant cut diamond is generally more expensive than a princess cut diamond at the same carat weight. A brilliant cut diamond retains 50% of the original stone while a princess cut retains approximately 80% of the original stone. An additional note about carat weight. Some stone will look bigger than others with the same carat weight. Some are wider, some are deeper, some settings will make the stone look larger or smaller. To sum it up, the Four C’s are a tool for analyzing a stone. But the real assessment of a diamond’s beauty should be made by you. Every antique diamond is unique. And that is one of the reasons they are so beautiful and one of the reasons they have such endurance. If their beauty could be quantified by a gemologist's spreadsheet one might as well buy a synthetic stone. I have seen gorgeous stones with lower stats--an O color, an I1 clarity. What that O color grading couldn't express was the warm golden color of that particular stone. And I have also seen stones with excellent stats, that seemed sort of, well, lifeless. So please, when buying a stone, use the 4 C’s to determine if you are paying the correct price but use your eyes and your instincts to decide if the beauty of a particular stone speaks to you.


All ISADORAS pieces of jewelry, where the price is dependent on the quality of stone, comes with a full independent appraisal from North American Gem Lab.

North American Gem Lab Credentials

Thomas B. Elliott established North American Gemological Laboratory, formerly Elliott Gemological Laboratory, LLC in 1998. Mr. Elliott has been in the jewelry industry since 1989. He is a graduate jeweler gemologist from the Gemological Institute of America (G.I.A.), and is a member of the GIA Alumni Association. He is also an affiliate member of the American Gem Society (A.G.S.) and member of the National Association of Jewelry Appraisers, (J.A.J.A.).