Cai.iforsia Diamonds.—The SacramentoUnion, of Jan. 17th, savs : “Assemblyman• •Smith exhibited to us. yesterday, several diamond rings, the stones of which were taken from Cherokee Flat, about ten miles from ^ Oroville. Some of the diamonds were sent, some time since, to Crosby A- Morse, lapidaries, in Boston, and were cut and polished by them in such a manner as to give them an appearanceequal to that of the most precious stones. Theywere found on the top of the black sand, whichall miners know is but a little lighter than golddust. Some thirty or forty of these stones havebeen found so far. Those who are curious onthe subject of California productions can see these specimens at Floberg's. on J street. •