Accredited Gem Appraisers

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Do It Yourself AGA/NAJA Cut Class grader

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Naples, FL 34114

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Diamond Education

Articles: Frequently Asked Questions

"What are ideal pavilion angles for emerald cuts? I have only found one source that says anything about pavilion angles for emerald cuts, and this author generalizes to include all fancy cut shapes. It says that pavilion angle for a fancy cut should be exactly 40 degrees, but can vary up to 3/4 of a degree while still only losing a small amount of light return. The author also noted that this angle is slightly different that than for rounds. Do you have a preference for this angle?"

You can see from my website I do not discuss angles on fancy shapes. That is because the angles vary on some stones since they are partially round. On emerald cuts there will be angles on the sides and at the ends. One cannot expect these both to be the same. It is better to have crown height, table size, girdle thickness and overall depth considered and let the angles take care of themselves.

"Another source said that this angle is not as important on a fancy cut stone. Is that true? Should I not be as concerned about it?"

I Agree.

"What are ideal pavilion angles?"

We just covered that above.

"As for crown angle, it seems that the consensus (of two sources) is between 32 and 35 or 36 degrees. Again, neither source says if this angle is critical or not, but I assuming it must be or they wouldn't mention it at all. Is this the case? Is that range acceptable? Or do you have a different range that you prefer?"

Crown angles also cannot be used for fancy shapes for the same reason that pavilion angles change as they go around the stone.

"One jeweler told me that all those angles and percentages are a bunch of bunk because depending on the L*W ratio they will all change and be different anyway. It's been a long time since I have taken geometry, but I didn't think that those angles would be dependent on any of the length or width measurements. Is that the case?"

I may not like his overall attitude, but in stones with rounded sides he is exactly right. In straight side stone, like an emerald cut, the angle on the width side is not the angle on the length side necessarily. The average angle overall would mean nothing.

"Is there an order of importance for all of the measurements? For example - is the depth% more important than the table%? Or, is it the other way around? Or should some other measurement, like crown height or crown or pavilion angle, be considered first? Or, should they all be taken together?"

Take them together and look at the stone. You will find it difficult to find a well cut emerald cut, but when you find a nice one, I'd bet some of the characteristics meet my AGA Cut Class specs. If you are lucky and patient enough to find one that would grade 2A or better, you will likely be seeing a very nice looking one.

"If there isn't information on the CERT about the crown and pavilion angles, is it safe to assume that they are in acceptable ranges if the depth%, table% and crown% are all within acceptable ranges?"

Crown percentage and depth percentage along with table percentage and total depth are all needed. NEVER ASSUME.

"Even with suggested ranges for measurements that are easier to find, like depth% and table%, there is still a wide range of what people find to be acceptable. This can be very disheartening for someone trying to pin down hard numbers :). Some sources say, 'It is a matter of personal preference and each stone has it's own personality.' I believe that is true to a point, but I can't help but think that it sounds like slick marketing for inferior stones at the same time."

It is slick marketing to say buy what you like. It is also a reality that an impulse purchase of something you really like is far more romantic than one that has been researched to death. I think if you eliminate overly deep stones and concentrate on stones that show their size, you will on the way to doing a better job. You can pin down numbers, but may never find a diamond built that way."

"If you find a stone that has most of its proportions in a very good range, say the 1A or 1B, but another proportion in the 3A range, would this be preferable to a stone that has all of its proportion in, for example, the 2A range. In other words, is it important to not mix proportions from different classes - will it look weird? - or do you want to get as many good proportions as possible, regardless of whether or not one may be from a different class?"

This is where the eyes and heart take over. No one can criticize a smart shopping decision when you have the facts.

"Finally, how important is any of this? Is my untrained eye really going to be able to tell that much difference when it comes right down to it? I'm sure in my mind I will think I see a difference, but I am afraid I may be susceptible to a few numbers on a piece of paper clouding my vision if that makes the slightest bit of sense."

Judging by the number of failed marriages, I'd say humans are not very discerning over the long run about many important things. If you can see a difference in a diamond from one to the next depends on your eyes and the lighting. I would use the AGA Cut Class numbers as a guide and not as a decision maker. I think using all your faculties is the correct way.

"I read your article on appraising on PriceScope, and really appreciate the insight as I'm currently in the market for a diamond. Can you explain to me why appraisal values are typically 2x or more than the purchase price of the diamond? Why don't diamond dealers sell diamonds at their full values? I appreciate your response."

Appraisal values on Insurance appraisals generally reflect not what you actually paid on the Internet, but what you'd pay in a full price retail store. We can make an appraisal for "Discount Retail" if it is wanted in order to save some insurance costs. Below that, you will take the risk of not being fully insured at some future date if a loss occurs. It is okay to insure a new item for exactly what you paid, but there is a risk involved in doing so. If the price was exceptionally low, then a replacement might be impossible. Also, there is no standard formula for retail mark-up. Most Americans like to think they are buying a "bargain" whether it is true or not. Look at all the phony sales at the shopping malls this Season. It is what we love to do... Deceive ourselves a little.... Some don't like it, but the majority rules in this I think.

What is the story and importance of Hearts and Arrows (H&A)?

The answer to this question can be found by clicking on the following links:


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