Dichroic Coated Glass FACTORY SHEETs arrive from the manufacturer, Coatings by Sandberg (CBS), typically in 19" diameter rounds. Depending on the base glass manufacturer (Wissmach, Uroboros, Bullseye, ...), the round sheets in some cases will have two flat sides approximately 16" to 17" inches apart. Dichroic FACTORY SHEETs can be cut down into 4 QUARTER SHEETS that are approximately 9½x9½" with a rounded side, as shown in the diagram below at left. If the FACTORY SHEET has been trimmed by CBS, then the QUARTER SHEETS will measure closer to 8½x9½" with a rounded side as shown in the diagram below at right. Please note that certain dichroic coatings (such as Rainbow 1) and patterns will result in very different looking QUARTER SHEETS depending on what portion of the FACTORY SHEET the QUARTER SHEET is cut from.Similarly, 4x4" pieces may also vary considerably in look for certain dichroic coatings (such as Rainbow 1) and patterns depending on what portion of the FACTORY SHEET the 4x4" piece is cut from.