Choosing the Right Core Drill for Stone Setting - Granite & Chalcedony

Question
I am planning on setting semi stones on top of one another or recessing tube sets in a larger stone for a ring. The tube OD is 4mm to 5mm.  The material is granite 11.25 at it's highest point.  The stone is a triange shape.  I also have chalcedony cads stones that lend themselve to have stones set on top.  What size core drill should I use?

Answer
Hello,

Here is a website to get your diamond core drills.
http://www.lopacki.com/coredrills/

You need the 4 or 5 mm OD size, I guess the 11.25 is mm?  If so you are okay with the drills on this page.  Keep the bit cool under water and go slow and easy you should use a drill press for this.

Good luck,  

Steven D.Covey