The better quality, the more facets, the larger the piece, the better the rainbows. A small 26mm leaf will create rainbows, but you may not see them often. Small pieces are great for jewelry, accents, or in small areas. If you are looking for something to hang in a window and spread rainbows throughout the room, then you will want something that is more the size of a 50mm prism or any of our sunclusters. We have had a small stream of sunlight hit a tray of sunclusters and send small rainbow dots throughout the room.