Do you provide country of origin of your diamonds?

It is generally not possible to independently determine country of origin.  Since diamond is pure carbon, only very sophisticated tests can sometimes reveal unique characteristics that might suggest one source vs another.  Most rough diamonds are distributed to manufacturers in specific assortments of sizes and qualities which requires mixing of crystals from a variety of mines.

Even a statement from a manufacturer with a high degree of confidence is not truly a guarantee since independent verification is either not practical or is inconclusive.