The concept is simple – just snap the gems together to create a complete ball. You'll be amazed at all of the possible combinations. The seemingly simplistic concept of this puzzle will rope you in, but you'll be amazed at how challenging it actually is to solve. Once you start, it’s hard to put down. All the gems on Mind Jewel are connected by a single string and do not come apart. The finished product is a 4" diameter ball. Being both small and self-contained, Mind Jewel is perfect for travel. Ages 6 and up"