Made from either quartz or glass, crystal’s qualities of clarity and transparency are the milestones of the fifteenth anniversary.
As demonstrated by Benjamin Franklin’s glass harmonica, crystal also holds musical properties. The resonant frequency of crystal creates beautiful tones, much as a harmonic couple brings joy to those around them.
Paraphrased from The Meaning of Wedding Anniversaries by Gretchen Scoble and Ann Field, Chronicle Books LLC, San Francisco, CA, 2004