NIB Teeth Brightening Purple Serum - SEALED BOX Yellow? Never Heard of Her. SNOW’s Purple Serum Has Your Back! An instant boost for your smile! This easy-to-use, travel-friendly purple serum uses advanced color-correcting to temporarily hide yellow teeth stains. Use it right before a night out, alongside your SNOW teeth whitening products for a big event, or anytime you need an instant confidence boost!