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Recommendation CAD manufacturing guidelines for claw prongs

Hi guys,

It seems like even Stuller CAD guidelines don’t mention this per se.

So I am wondering what is a recommended distance or height of the prong from the table if I want it be claw shaped during setting. I am getting varied answers to this from .75mm above table to 3 to 5mm above the table.

To be specific, the center stone is a 1.5ct emerald cut (roughly 7.5 x 5.5mm). The ring will be printed on a solidscape and cast into platinum.

Also what do you recommend the diameter for the claw prongs.

Thanks,
Rumi

As I have only a few days (21,900, to be exact) of Diamond Setting experience, here is my rule.

I NEVER have the tip of the claw, this is after filing, trimming & polishing to be above the “Table” of the stone. No matter the size of the stone!! If you have the claw above that height, the wearer will literally catch the claw on some clothing and it will move it away from the stone, this will lead to having the stone be loose!!!

To repeat this again; the very tip of the claw must never be above the Table, no matter if it’s a Princess, Round or Emerald-Cut stone. Other people might disagree with me, but I’m comfortable with this ruling!. I hope this helps you and all!


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Keep in mind that when Gerry says, quite rightly, that the tips of the prongs must be lower than the table he is talking about the finished height of the prongs. But the prongs start out significantly taller to facilitate ease in pushing them into contact with the crown.
Personally I don’t much like cast prongs, especially for a larger stone. I’d suggest rather than casting the prongs leaving space for drawn wire to be soldered in after casting and cleaning.
As to the diameter, since it’s an emerald cut stone if you do double prongs at each of the four cut corners the diameter can be no more than one half the length of the corner facet at the girdle.

Hi Elliot,

Thank you so very much, for showing the “double-claw” diagram. Between us both, I think we got this question nicely answered, agree?

Yes I am not talking about finished height of the prong. I am talking pre cast in this case a CAD file that will be 3d printed.

You mentioned significantly taller. This is precisely my question - how much significantly taller? Is there a general rule of thumb esp. if they will shaped into claw vs a regular prong setting? Is the height dependent on the stone size?

Thanks for the solder tip. For this particular ring it is not an option but good to know.

About the diameter, that is a great tip as well. Wish GIA published detailed dimensions of the stone so I could know the corner length. I have heard some people actually scan the stones and design around that.

Wow that is twice by age. You are legend Gerry. Thanks for sharing your knowledge!

Your rule definitely make sense. But as Elliot mentioned I was not talking about finished prongs. I am talking about prong at the wax stage. I should have clear about this in my original question but I thought it was implicit since I was talking about CAD.

The Stuller CAD guidelines (see page 3) recommend to keep the prongs at the same level as the table. But this is for regular prongs and not claw prongs per se. What I am hearing from talking to some people is to make the prongs longer so the setter has room to shape the prongs into a claw. So my natural question is how much taller than the table.

“I’m not old, but overly mature”. That being said, get those tips either in wax or metal long enough to be able to fit the claw closer to the stone. I stated before a “3.50-4.50” mm’s. This will give more ease & leverage than a short claw!!

From the information you supplied, send us your photo of your CAD images. Then we as a group can help you further!

Gerry, on my ”Raptor’s City” iPhone

Just one more thing about being able to bend the long claws. Once the setter creates the bearings for the Girdle of that stone, the claw will be able to bend MORE freely and less effort as you originally thought. Also, think of this, you are not bending the whole long claw, per se…you are bending the very tip (from the Girdle) and upwards that will now hold the stone in place.

I always speak less more practicle :grin::grin::grin:

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