Koltose by Mash - Flat Glass Marbles are all made of the highest quality glass and are non-toxic. These marbles were made with the finest craftsmanship reducing flaws and blemishes common in other marbles. Use as a vase and bowl filler or as a table scatter at your next party. Use as a wedding and party d?cor or simply around your house. Place them in your fish tank aquarium or use them as crafts supplies. Essential for home decorators party planners and as props for photographers. The color of these marbles is a deep non-transparent blue with a slightly reflective polish allowing these marbles to properly conceal flower stems in floral arrangements on your aquarium floor and providing greater contrast for table scatter and centerpieces.