KRYS-TOL was first used by Ohio Flint Glass Co., Dunkirk, Indiana (had nothing to do with actual 'flint' glass, however - just a name of the company). this was in the late 1890s. in 1900, Ohio Flint merged with National Glass Company, making a huge combine of manufacturers. In 1907, Jefferson Glass Co., Follansbee, West Virginia, bought all rights, patents, and molds from National Glass. KRYS-TOL was a process, used in various lines, the most popular being CHIPPENDALE. By Oct. 1908, Jefferson Glass was making CHIPPENDALE in 100 different shapes, gearing up to 150 in the near future. On Dec. 26, 1918, all rights, patents and molds for KRYS-TOL 'CHIPPENDALE' were sold to Central Glass Co. the number of molds totaled a little over 400 by that time. Central expanded their market share to distributors in Denmark, Germany, Norway, England, Scotland, France, Spain, Holland, Sweden and even to India and China. In 1929, the patents were sold to Charles J. Pratt of London, England.
Pratt had Geo. Davidson & Co. make the CHIPPENDALE line. Eventually, Davidson bought the molds from Pratt. It is believed, however, that this Chippendale was never marked with the Krys-Tol Mark.
Your piece was most likely either made by Jefferson or Central Glass.
the best book (by far) is KRYS-TOL! CRYS-TOL! KRYS-TOL! by Joan Chapman Loomis, self published in 2001. ISBN number is 0-9712272-0-9. I do not know if it is still available, other than the used market. I don't have contact info for Loomis. When I got my copy, she was living in Florida. The back of the book lists this address: JEAN CHAPMAN LOOMIS, P.O. BOX 111, TAVARES, FL 32778.