This is an excellent example of a large 25/32" mint condition Christensen Agate Company Flame Swirl. The surface is glassy. While this red-and-yellow color is not extremely rare, it is highly desirable with collectors of top-shelf vintage CAC marbles. This oversized CAC Flame Swirl in this color combination is one of the best I have ever seen in hand.
Size measured at the widest point with digital calipers.
Photographed with no editing or enhancement, so you can judge color and surface honestly.
