VERY INTERESTING . THESE ARE COLORED GLASS GREEN RED AND ORANGE BASE COLORS AND THEN EACH ONE ROLLED INTO COLORED GLASS CHIPS. SO THEY ARE NOT COMPLETELY FLUSH SMOOTH MARBLES. THEY ARE A BIT BUMPY. I HAVE HAD THESE FOR 30 YEARS. IVE NEVER SEEN THEM BEFORE AND I DONT KNOW WHAT TO CALL THEM. THESE ARE JUST DIFFERENT AND UNIQUE EACH IN THEIR OWN WAY