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Author Topic:   How do you evaluate the cut of the Lucida diamond? + where else can you get it?
Romeo
rough rock

Posts: 7
From:Ottawa, ON, Canada
Registered: Oct 2001

posted 10-23-2001 07:15 PM    
Can we get Lucida cut Diamonds from other vendors other than Tiffany's (by another name)? What is the name of the cut. How do you evaluate the cut of the Lucida diamond (angles, etc.)?

 
oldminer
cut rock

Posts: 128
From:Philadelphia, PA
Registered: Sep 2000

posted 10-24-2001 09:55 AM    
There are similar cut diamonds. I know one is called a Lucere rather than Lucida. There is another one also other than the Lucere, it begins with an "L" also, but I can't think of the name.

As far as I know, only TIffany & Co. Sells the Lucida.

One must judge the quality of the cut by comparison with other diamonds. this is not easily done by the consumer and there is no easy method for me to suggest. You really need expert asistance when it comes to that sort of judgement.

------------------
David Atlas
Accredited Gem Appraisers

 

mbn
cut rock

Posts: 72
From:Laguna Hills, CA, USA
Registered: Sep 2001

posted 10-26-2001 04:26 PM    
it seem the lucida diamond fr. Tyf looks larger than a round, corners are tapered, and shines and shines.

 
Cut Nut
cut rock

Posts: 312
From:Melbourne Australia
Registered: Aug 2000

posted 10-26-2001 06:51 PM    
Luida is a way of getting a 1ct diamond from rough that would yeild a .80ct ideal cut and charging a lot of money = profit for Tiffany who have registered the cut and trade name.
The spread is very very poor.
A fair comparison is with old cut diamonds. The science behing the cut is a retro step.

 
Romeo
rough rock

Posts: 7
From:Ottawa, ON, Canada
Registered: Oct 2001

posted 10-27-2001 05:07 PM    
What exactly is a spread? I looked at the description on the tutorial page and it didn't help very much.

Thanks
 

leonid
Moderator

Posts: 976
From:Toronto, Ontario
Registered: Jul 2000

posted 10-27-2001 06:48 PM    
did you see this page: http://www.pricescope.com/tutor_spread.asp ?

You can consider spread as a diameter at the given weight. Depending on cut different diamond can look larger or smaller yet have the same carat weight.
 

Romeo
rough rock

Posts: 7
From:Ottawa, ON, Canada
Registered: Oct 2001

posted 10-27-2001 09:55 PM    
I saw the page but it didn't really say what the spread is. From what I understand now, basically it is a top surface area to carat ratio... sort of a cut's top view efficiency.

It makes sense that different cuts have different spreads, and that different quality of cut will affect the spread (I guess that is what the page was trying to say - I just didn't get it the first time).
 

Cut Nut
cut rock

Posts: 312
From:Melbourne Australia
Registered: Aug 2000

posted 10-28-2001 05:22 AM    
More about spread for round diamonds.


Spread or apparent size of a diamond is the most important factor to many diamond buying consumers. Spread has been ignored in previous cut grading systems, but HCA compares and rates it.

A diamond that looks bigger than another is not necessarily more beautiful, but it is more desirable. A diamond of the same weight but larger diameter is said to ‘spread’ more. Spread is a matter of desirability rather than a beauty factor.

Size equals ‘desirability’.

First time consumers often mistakenly consider the spread of a diamond to be directly related to its weight. Even within the trade, the depth percentage is used as a value factor in determining spread, but depth percentage is a poor metric because girdles and crowns have more impact on weight a diamond’s pavilion.

For many consumers everything about the beauty of a diamond is salesmanship, because after all even ugly diamonds are beautiful; to some size is all that counts, and having advice about the size rather than the weight is critical.

So given the importance of spread, why has it been completely ignored?

These 2 diamonds both measure 5.2mm in diameter, but the 0.65ct lifeless one is 20% deeper than the 0.50ct ideal cut.

The HCA system calculates a spread penalty for a diamond based on the three main geometric components: crown, girdle and pavilion.

We choose to give a zero penalty for a diamond with a 40° pavilion, 32.5° crown, 58% table and a 1% girdle, diamonds with better spreads also rate zero. The worst score of 2.0 is given to a diamond with a 10% girdle, 40° crown, 54% table and 43° pavilion. Stones with even worse spreads are not further penalized.

Romeo you can compare the spread of a princess cut to a round diamond by this arithetic -
Spread of princess cut = LXW
Spread of round diamond = 1/2 diameter x 1/2 diameter x 3.142
Expect lucida / radiant / princess will have much smaller spread.


 

leonid
Moderator

Posts: 976
From:Toronto, Ontario
Registered: Jul 2000

posted 10-28-2001 07:35 AM    
Good explanation Garry. Shall I add it to the Spread page?

 
Romeo
rough rock

Posts: 7
From:Ottawa, ON, Canada
Registered: Oct 2001

posted 10-28-2001 11:09 AM    
OK, so I think this is my last question - sorry for the newby questions...

What is the radius of an ideal cut round 1 carat stone - and what is the length (or width) of an ideal cut 1 carat lucida (I guess it is kind of octagonal table, not square? - are the outer dimensions square)

I think you can see where I am going here, what is the spread difference for a 1 carat lucida versus 1 carat round. In an earlier post I got the impression it is about 0.8 (Lucida) to 1 (Round) ratio.
 

Cut Nut
cut rock

Posts: 312
From:Melbourne Australia
Registered: Aug 2000

posted 10-28-2001 01:46 PM    
How long is a piece of string, there is a range of diameters 1ct can be from 6.3 to 6.65mm.
And an ideal cut lucida is any oxymoron Romeo.

 
Romeo
rough rock

Posts: 7
From:Ottawa, ON, Canada
Registered: Oct 2001

posted 10-29-2001 07:04 PM    
As an engineer, I would say the string is 6.475 +/- .175 mm. What about the dimensions of an equivalent rating of "Fair" or "Good" for a Lucida cut?

 


 
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