Straight Talk on Angles

[hughmcg]

Arrgghh! The longer I look, the more I read, the more I learn, the more I''m confused.

Whew! Sorry.

How important are guidelines (such as set out in Fred Cuellar''s book among other places) for Crown and Pavillion angles? Other measurements? For instance, they say total depth should be between 56 - 61 and anything above 61 I should walk away from. The jeweler I''m dealing with showed me a chart that says total depth can be acceptble up to 63+!!

Another says that pavillion angles should be 40 - 41.5. All others are disqualified.

Am I potentially letting a good deal get away? What should be the non-negotiables?

 

[quaeritur]

It depends what you want. Personally, I'd at least narrow it down to AGS ideal proportions or a 1A or 1B cut (you can find a stone's cut grade by entering its dimensions here.

Oh, and I'd toss the Fred Cuellar book in the trash and start over with the tutorial on this site (link at top of page).

If you post more details on the stone you are considering, I'm sure folks here will be happy to give you some opinions about how it might measure up. Don't be afraid to ask questions!

 

[oldminer]

Non-negotiable issues depends on you, your taste AND your budget. Look with your eyes at finely cut stones, reduce the cut quality to the point that you can see a difference. That will save you quite a bit of money, but the diamond won't be an Ideal or premium cut probably.

Do the same with color and clarity, if you dare, but you will not choose a D - Flawless by this method.

Then, of course, you could do the same thing with weight. Look at a 1.00ct stone and then see if you can tell the difference at .95ct. You might not be able to.

You could very well get a diamond that pleased you that was nowhere near ideal cut, the weight you thought you liked, the color or clarity you believed you required. It would cost a whole lot less, too.

Do the angles matter? Not as much as common sense matters, but they do matter....

 

[Paul-Antwerp]

Hi Hugh,

To start, take a deep breath and relax.

First, a question: what do you want? Do you want a super-performing stone or do you wish to settle for a mediocre stone for a decent price. Maybe, a combination of great performance and a great price is possible.

Then a remark: I once learned that there are two types of people who fail in their efforts. The first group takes nobody's advise. The second group follows everyone's advise. You have to try to choose whose advise you will take. To give you some help: I would throw away the book of Fred Cuellar, he is a known fraud. As for your jeweler saying that depths of 63% are totally acceptable, please read this tutorial and other studies that this site might direct you to, and then decide if your jeweler knows what he is talking about. Do not be surprised if you decide that he knows less than you, after you finished your small study.

Finally, step back and look at the drawing of a diamond from a distance. There are some basic rules.

To start, when total depth increases, the diameter and the spread of the diamond decrease, thus your diamond will look smaller.

Second, you have to be very critical of the pavilion angle, and depending on how good a performance you want, the range of pavilion angles becomes narrower. Please remember that 0.2 degrees in pavilion angle make a real difference. A range of 40 to 41.5 is comparable to the distance between NY and LA.

Third, pavilion and crown angles work together. Once you have all the info on a possible stone, run them through the HCA, which you can find here on Pricescope. If you get a decent score here, you can go more into detail and check the stone visually.

Finally, if you have any question during your search, we are here to assist you. Any question posted on this forum will get a high number of replies. Again, you will have to follow some, and disregard others, but the quality-level of replies here will be definitely higher than elsewhere.

Good luck on your venture,

 

[jesrush]

Despite Fred's shady "bonded diamond" antics, his advice in 'How to Buy a Diamond' is fine (at least as far as proportions go). If I remember right he reccomended crown angles in line with AGS0 and pavillion angles in the 40.6-40.9 range, he singled out 40.75 as an ideal target. That's fine.

His depth reccomendation is basically fine too... look for 59-62%. 63% is too deep for awesome light return.

Really, just head over to superbcert.com, niceice.com, and goodoldgold.com and look at the crown & pavillion angles and depths of the stones on those sites.

Here is a direct link to a good guide:
http://www.niceice.com/5_minutes.htm

-J