John Van Koningsveld’s career in stained glass began in 1991 when, as a collegiate art major, he began an apprenticeship with James P. Schlitz, owner and founder of Schlitz Studios and Schlitz Furnaces. Most of his study focused on Louis Comfort Tiffany and the production of his Tiffany Studios, as his works were the most well known and commonly reproduced. He studied in depth not only the processes for creating leaded glass shades and windows but also the history of these designs and the artists that created them, and even had the unique experience of repairing and restoring a number of original Tiffany pieces. Under Jim's tutelage, John made hundreds of reproduction shades as well as a few windows. He had the rare opportunity to assist Jim in his glass foundry, manufacturing sheets of glass that were equal to or exceeding in brilliance the original Tiffany glass he was trying to emulate. This was his introduction to hot glass, running ladles of molten glass to be hand mixed and hand rolled; it lit a fire within him. All of these products were marketed world wide and the reputation of both companies stood head and shoulders above all competitors. Upon Jim's untimely death in 1993, John elected to stay with the studio and continue Jim’s fine tradition of Tiffany reproduction lamps and windows; he even had the opportunity to create a few original design pieces in the Tiffany style. He remained with the studio until early 1998, becoming the head of production and design during those final years.