C/W and P/W, what do they mean?

[FlashGP]

Have you noticed the numbers on modern daceting diagrams like L/W = 1.25 P/W = 0.564 C/W =0.175 and not known what they mean?  Don't worry lots of facetors are not sure what they are.

They are ratios of the length of the dimensions on the diagrams on the faceting diagram above the numbers.  L/W is rhe length width ratio.  If your rough is say 11 x 14mm then this ratio says you can probably get a 10 x 12.5mm stone from it but if your rough is 11x13mm you can't.

C/W is the crown height.  Add the girdle width (say 3% of W or 0.03) and a but for cutting and you can work out how much you have to have to cut the crown.  So if your stone is 11mm and fough for the crown is 1.5mm in this example you need at least 2.3mm to cut tge crown so you have to reduce the size of the stonene wwhen cutting the girdle until the meat for the crown is more tha n 0.205 tomes stone width plus some to cut the table.

C/W + P/W + girdle width (say 0.02) is the finished height of the stone if the girdle is 2% of W.  Allow a bit more for cutting, say 2mm, more if there is a big change in pavillion angles or your design has a preform. 

The stone I am cutting has pav angles starting at 55 degrees and finishing at 40 degrees.  This means I needed about 0.2W more material than the finished height to accommodate the material cut by the 2nd to 6th rows of facets.  When I thought I could get a 12mm stone from the rough, I'm gettimg a 10.0 mm stone.

Happy faceting

[FlashGP]

PS I'm not the policeman from Allo Allo, I'm  typing om my phone and should proifread before posting.  Sorry.

Tomes =times
Frough = rough
Etc.

[Jimnyjerry]

PS I'm not the policeman from Allo Allo, I'm  typing om my phone and should proifread before posting.  Sorry.

Tomes =times
Frough = rough
Etc.

 

[FlashGP]

Report to moderator Logged 

Careful Jimnyjerry or I'll ave to ask Michelle from the Resistonce to piss a messarge on to vou. 

[FlashGP]

PS..  to everyone not acquainted with Allo Allo, the policeman is an Englishman maskerading as a Frenchman during the German  occupation of a French village ... and mashing tbe French Language in much the same way my fingers do the tiny keys on my phpne.

[Aussie Sapphire]

PS..  to everyone not acquainted with Allo Allo, the policeman is an Englishman maskerading as a Frenchman during the German  occupation of a French village ... and mashing tbe French Language in much the same way my fingers do the tiny keys on my phpne.

Listen very carefully, I shall say this only once: 

"Carry on Flash - the faceting advice given here is very useful and appreciated by admin"


 


Cheers
Leah   (aka "Michelle")