Brandy, Cognac, & Whisky Bottles are usually the top of the line of most sophisticated glass bottle manufacturers. At Rockwood, we pride ourselves to offer the purest and whitest super flint glass, very close to crystal transparency. What will create the value of a decanter and bring light to the product is usually the thickness of the glass slug at the bottom, crystal clear without any bubbles or shadows. Many secondary glass manufacturers will deliver uneven glass slugs. In the past few years Rockwood has acquired the latest cutting-edge technology that will make each and every slug perfect even with an absolute transparency.