Potomac Crystal Rivoli 18mm - Siam AB. These high quality rivoli feature a pointed foiled back to increase the reflection and add dazzling sparkle to your projects. These crystals have no holes and can be used with a variety of bead weaving and wire working techniques to include them into your designs. Be inspired and get creative with the many sizes and colors available. The Potomac Crystal Rivoli can be used in designs calling for Swarovski 1122. They measure 18mm and come in a pack of 2.