Just curious, after I create a new surface 7 degrees off the cleavage plane, should that new surface then be the crown side of the new stone, or does it matter?
I don't know about a rule, but polishing a topaz table parallel to a cleavage plane would probably result in flaking, chipping, chattering or some other faceting undesirable.
7 degrees is probably the minimum to avoid the undesirable. Table orientation will probably depend on the rough and the " minimal rule."
Joined: Thu Jun 03, 2010 1:49 pm Posts: 331 Location: South Africa
Nickarnight,
To be a little more clear, the table is best about 8 degrees off the cleavage plane, this will ensure that none of your crown facets are at an angle that would make them susceptible to cleaving should they receive a knock once set. If you had to rotate the stone 90 degrees to facet, there would be a danger that a crown facet may end up on the plane and give you a hard time polishing. Also not a good idea to have the girdle too near the plane either as it may cleave while being set. An easy way to stay out of trouble is to make the plane on the rough and place it on your drawing, that way you can rotate it around to see how your rough can be orientated and still be sure of not picking up any problems.
Joined: Thu May 29, 2008 8:32 am Posts: 1730 Location: Suwanee, GA US
And a trick from John Campbell here in Atlanta. Get a dop and a lap you don't use. Set your angle adapter to 45 degrees. Insert the dop and now change the angle to 38 or 52. Grind this 7 degrees into your dop. Now you have a dop you can mount on the clevage plane and it will put the 7 degree correction in.
Users browsing this forum: No registered users and 15 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum