I have never seen this chip attributed to Circus Circus, LV or Reno, which opened in 1968 & 1978, respectively. This small 26 diamond mold was used in the 40's & 50's.

When you first posted this chip you said that TGT listed a "CC" DIAMND mold as unknown. There are other molds of "CC" listed in TGT as unknown but not the diamond mold. However, there is a diamond mold listed in TGT-2 on page 55 as CC (Alamo Club) Pioche, NV. I got this chip from L.C. Meredith along with 5 Alamo Club chips in about 1987. L.C. was told that the CC was used at the Alamo.

Since then, I have learned that the "CC" was made for the Caliente Club in Caliente, NV. It is listed in TCR-7 on page 31 and a pictograph of the "CC" is on page 319. It is V2237. You can see that it is not the same "CC" as the Ebay chip, which may be revealed as a good chip some day, but for now it is unknown.