I would imagine that you would probably only use water for
sawing gemstone material. That is what use here in Brasil - in
The “best” lubricant is contingent on the material which you cut.
If you are cutting hard/tough material such as agate or jasper,
water is not the optimum, even with additives. You will burn out
sawblades prematurely, which is expensive as well as inconvenient.
For such tough materials, IMO, you would be well advised to use an
oil-based lubricant such as Almeg oil.
If you are cutting material which is porous and which will be
stained by oil, e.g., turquoise or variscite, you will want to use
water as a lubricant.
For stones which will not stain but which are not particularly hard
or tough, either oil or water-based will do. If you do use water,
you would be well-advised to use an additive to prevent rust and
Dos Manos Jewelry