Peach colored, embossed with letters resembling "KV/JL/T" inside of a shield. The J and L are not standard Cyrillic letters, so this may be from another former Soviet Union nation (Latvia, Lithuania, Estonia?). The "L" may be a stylized "C" as well, this one is still a mystery...

Update Nov 2009:

There is some thought it may be from Ukraine, but the letters are definitely NOT Cyrillic. The "J" and "L" look more old style German, the "L" with the curved uppewr part may be a stylized "I", in which case the marking would be KV / JI / T This may be a CD 579 or 570.5 (?) . I also have an aqua / blue unembossed "twin" to this, and another one of the same physical size, in dark green with a stylized "EKO" inside of a circle, and is from Estonia.

Update 25 March 2010: Thanks to Donald Mecklenborg, this insulator has been identified. see [id=274044225] KV stands for Klaas Vabrik (Glass Factory); The letters J, L and T stand for Johannes Lorup, Tarbeklaas, Scankristall and Glasstone. The J. Lorup glass factory was called Meleski prior to 1926 It is from Viljandi County, Estonia.

[IFONA CD 570]