Have you ever seen wine in a wine glass? Its luster is warm like amber or sometimes bright like a ruby. Once wine has been consumed, the residue at the botttom of the glass sparkles like gemstones after air-drying and crystallization! During the fermentation of grapes, as alcohol level rises, the solubility of tartarates decreases, making it easier for them to form crystals. Place a drop of red wine on a slide. Once dried, view under a polarizing microscope. As the tartarates crystallize, they become birefringent. Due to differences in composition and thickness, colors fluctuate and blur, forming unique shapes. Actually, red wine can be thought of as liquid rubies.