How to drill holes into Gemstones and other objects? Get A Good Drill Bit

I have been tearing my brain apart trying to find drill bits that are small enough to drill holes into 8 or 9 mm oval Gemstones and beads. The bit has to be tough enough to drill through the stones ( some of which are high on the Mohs Hardness scale) but small enough to produce a 1.5 mm or so hole in the stones. This is not an easy feat.

At Onsrud Cutter LP, they have drill bits for all uses, from wood drill bits used for woodworking furniture and also for the Construction business. They produce plastic drill bits as well and have a large selection and PDF's for your reading right on the website.

They make their bits from High Speed Steel, Carbide and Diamond tipped. I think I need the Diamond Tipped Drill Bits for my needs. I need to make sure that the drill bit does not get dull with just one or two applications or that would be very costly for me, and the bit needs to cut a clean hole so I can string the stones. I am not sure what Jewelers use, but I am hoping that I can locate a cheap alternative at this company.