We stumbled across the Frequently Asked Questions on the Preciosa website and thought you might be interested!WHAT DOES "GROSS" MEAN?A gross (often abbreviated as "grs" or "gro") is unit of measure used in the jewelry industry in the purchase of large volumes of components. A gross represents twelve dozen, or 144 pieces. Our components are packaged into envelopes or standardized boxes in the multiples of grosses ordered. Another unit of measurement frequently used for larger items is the dozin (abbreviated as "doz"), which represents 12 units. A full conversion chart is available in our Product Catalogue.WHAT IS "FOILING"?Foiling, first developed in 1878 in Crystal Valley, is the application of a reflective “mirror” layer to underside of a stone to give it maximum brilliance. Typical foiling layers include aluminum, silver and “gold” (a silver layer with an additional bronze protective layer). In 2011 the Preciosa Research and Development team created the revolutionary new Dura-Foiling™ layer, which gives crystal components higher brilliance, better adhesion (hot-fix) and even better processing resilience during secondary manufacturing.WHAT ARE PP AND SS – AND HOW DO THEY CONVERT TO STANDARD MEASURES?Crystal jewelry components come in many different colors, shapes and sizes. Three units of measurement are typically used when sizing fashion jewelry stones: pp, ss and mm. PP (Pearl Plate, or sieve size) is used for round stones, such as chatons. SS (stone size) is typically used for chatons and chaton roses. MM (millimetres) is usually used for other components such as fancy stones, beads or chandelier trimmings. The units are fully convertible, for example: SS 00 = 2 PP = 0.9 – 1.0 mm.Conversion Chart LINKWHAT MAKES A STONE “HOT FIX”?Hot-Fix refers to flat back crystal components that have a special low melting-point adhesive applied to their base (underside). This allows the stones to be applied to a variety of materials, including elastic fabrics and leather,