Hidden Culet?

[kelmel]

Should a diamond culet be hidden down in a setting (6 prong)? The jeweler has advised the culet will be down in a "little hole" at the bottom of the setting. Opinions??

 

[marymm]

It depends on the actual setting - it is not uncommon - but if your preference is to see the culet, your jeweler should be able to accommodate that preference.

 

[kelmel]

If the culet is hidden, will the diamond still have as much fire and brilliance? The jeweler said another reason for having the culet "hidden" was due to the fact that the setting would be higher up. It already sits up fairly high.

 

[yssie]

If the culet is hidden, will the diamond still have as much fire and brilliance?

Makes no difference (as long as the only part of the diamond that is actually touching metal is where the girdle sits in the prong-seats).

 

[pyramid]

I have seen some ring settings lately, where a solitaire has a two small diamonds set either side of the diamond in the foot of the setting, one facing the person wearing it and the other facing your nails. The tiny diamonds are prong set or bezel set. With these rings the culet is covered up from the side view. I don't know if this is a style from one of the big jewelry houses e.g. cartier, tiffany etc but I like it. This is in the UK I am seeing this.

 

[yssie]

I have seen some ring settings lately, where a solitaire has a two small diamonds set either side of the diamond in the foot of the setting, one facing the person wearing it and the other facing your nails. The tiny diamonds are prong set or bezel set. With these rings the culet is covered up from the side view. I don't know if this is a style from one of the big jewelry houses e.g. cartier, tiffany etc but I like it. This is in the UK I am seeing this.

Do you mean like this?

 

[Cricketcat]

Yssie,
You've answered a question I've had about the only place a diamond should touch the metal is in the prong seats. Is this for the safety of the diamond?

 

[WinkHPD]

If the culet is hidden, will the diamond still have as much fire and brilliance? The jeweler said another reason for having the culet "hidden" was due to the fact that the setting would be higher up. It already sits up fairly high.

I believe that what your jeweler meant was that if the culet was not in the small hole that the setting would then have to be higher up. Putting the culet into the hole allows the diamond to be set a little lower.

FYI, it is a common misconception that having an open mounting on the bottom allows light to enter the diamond and provide better sparkle. Unless you are talking about a very poorly cut diamond, this is simply not true.

The vast majority of light that you are observing in a diamond is light that has entered the diamond from the crown (top) portion of the diamond, and reflected back out of the diamond from the pavilon (bottom) portion of the diamond. The better the cut, the better the light return.

The best reason for having an open style mounting is that it is easier to clean the pavilion of the diamond, which is a major component of keeping your ring looking like a sparkle factory. A dirty pavilion allows more of the light coming into the diamond from the crown to leak out the pavilion of the diamond rather than being reflected back up and out of the crown.

Wink

 

[cflutist]

If the culet is hidden, will the diamond still have as much fire and brilliance? The jeweler said another reason for having the culet "hidden" was due to the fact that the setting would be higher up. It already sits up fairly high.

I believe that what your jeweler meant was that if the culet was not in the small hole that the setting would then have to be higher up. Putting the culet into the hole allows the diamond to be set a little lower.

FYI, it is a common misconception that having an open mounting on the bottom allows light to enter the diamond and provide better sparkle. Unless you are talking about a very poorly cut diamond, this is simply not true.

The vast majority of light that you are observing in a diamond is light that has entered the diamond from the crown (top) portion of the diamond, and reflected back out of the diamond from the pavilon (bottom) portion of the diamond. The better the cut, the better the light return.

The best reason for having an open style mounting is that it is easier to clean the pavilion of the diamond, which is a major component of keeping your ring looking like a sparkle factory. A dirty pavilion allows more of the light coming into the diamond from the crown to leak out the pavilion of the diamond rather than being reflected back up and out of the crown.

Wink

Totally agree here. What I have noticed already is that my new CBI diamond looks so much whiter than my pear when viewed from the top even though they are both F in color. Superior light retun from my CBI diamond is the reason.

Having an accessible pavilion was the major reason I chose the Vatche Serenity setting for my new diamond. I can stand at the kitchen sink and clean my diamond with a soft toothbrush and liquid detergent without even removing the ring from my finger.

 

[yssie]

Yssie,
You've answered a question I've had about the only place a diamond should touch the metal is in the prong seats. Is this for the safety of the diamond?

It's not for safety but for light return. Diamonds return light per Wink's description:

The vast majority of light that you are observing in a diamond is light that has entered the diamond from the crown (top) portion of the diamond, and reflected back out of the diamond from the pavilon (bottom) portion of the diamond. The better the cut, the better the light return.

This internal reflection of incident light depends entirely on critical angle (the angle above which total internal reflection occurs), which is a function of the index of refraction of two media - diamond (~2.42) and air (~1). In this scenario critical angle would be
Θcrit = sin^(-1) (1.000/2.42) = ~24.4deg.

A dirty diamond is essentially diamond coated with a layer of grease, and the index of refraction of grease is different from that of air - this changes the angle at which light travelling inside the stone must hit the diamond/air bound to be reflected internally, and since diamonds aren't faceted to optimize total internal reflection at this angle more light "leaks" out the pavilion.

When diamond touches metal the entire model of total internal reflection is irrelevant because the diamond/air bound is now a diamond/metal bound. Metal doesn't permit transmission of light - all that's happening here is light inside the diamond being reflected off the surface of the metal back into the stone... the problem is that that inner metal surface won't be nearly as flawlessly-polished as the diamond surface, if it's polished at all - causing light to be reflected at different angles (uneven surface = unpredictable normals) perhaps back into the stone, perhaps not. An unpolished surface will absorb more light, meaning that less energy is reflected back into the stone, which results less bright and bold outputs. It's worse if it's a coloured metal - in this case the light that is reflected back into the stone is now whatever colour the metal is!

 

[pyramid]

I have seen some ring settings lately, where a solitaire has a two small diamonds set either side of the diamond in the foot of the setting, one facing the person wearing it and the other facing your nails. The tiny diamonds are prong set or bezel set. With these rings the culet is covered up from the side view. I don't know if this is a style from one of the big jewelry houses e.g. cartier, tiffany etc but I like it. This is in the UK I am seeing this.

Do you mean like this?

Yes that is maybe where the craze has come from. The ones I have seen, only seen two though were not a famous brand name but were like that without the pave diamonds or the bezel, just gold with prongs and the little diamond in the centre. I liked the look.

 

[pyramid]

I have seen some ring settings lately, where a solitaire has a two small diamonds set either side of the diamond in the foot of the setting, one facing the person wearing it and the other facing your nails. The tiny diamonds are prong set or bezel set. With these rings the culet is covered up from the side view. I don't know if this is a style from one of the big jewelry houses e.g. cartier, tiffany etc but I like it. This is in the UK I am seeing this.

Do you mean like this?

Yes that is maybe where the craze has come from. The ones I have seen, only seen two though were not a famous brand name but were like that without the pave diamonds or the bezel, just gold with prongs and the little diamond in the centre. I liked the look.

 

[diamondseeker2006]

It is extremely important to be able to reach the pavilion of the stone with a brush. So I am a little hesitant to do what your jeweler is suggesting unless there is a really big opening below the stone!