Tiffany developed a whole range of unique glassware by trying out and perfecting new techniques in the furnace. The glass itself was of the best quality, its colors achieved by the addition of metallic oxides, variable by temperature within the furnace. His lustering technique, with its iridescent effect, was the most important because it was his hallmark, used in many different wares. This involved dissolving salts of metallic oxides in the molten glass, so creating the chosen colors -- soft greens, blues, golds, etc. The metallic content was then brought to the surface by subjecting the glass to a reducing flame and spraying with another chloride. This treatment caused the surface to crackle into a profusion of tiny lines that refracted light. The skill of the blower was paramount in this, because Tiffany glass was free blown. Speed was necessary to achieve the desired effect before the molten glass cooled.

Lamps of Tiffany