This is a natural transparent yellow Chrysoberyl. This gem comes the same family as Alexandrite so it has a beautiful sparkle to it. Yellow Chrysoberyl is a beautiful gem that can be confused with lemon Quartz or yellow Zircon.
Ordinary Chrysoberyl is yellowish-green and transparent to translucent. When the mineral exhibits good pale green to yellow colour and is transparent, then it is used as a gemstone. The three main varieties of Chrysoberyl are: ordinary yellow-to-green Chrysoberyl, Cat’s eye or Cymophane, and Alexandrite.