How close to perfect does it have to be? This CD 109 is base embossed CHICAGO INSULATING CO. PAT. OCT. 16, 1883. There is a small open bubble on the base but it does not affect the embossing. The only problem I can find is a very small nibble on one of the diamond cuts. This is an outstanding insulator that I have priced about half way between the guides price range. $2700 with no premiums to pay. As a matter of fact, time payments are not a problem.