Blue Agate: Background, Significance, Therapeutic Benefits, and Properties Blue agate is one of the rare gemstones that truly captures inner beauty. Let's first talk about what agates are before we get into our subject about blue agate. One type of chalcedony is agate. When viewed outside, they appear repulsive and less appealing. But when these stones are cracked open, the inside is brightly patterned and attractively banded. Agate's interior features banded shapes and vibrant colors. These agates are used to make gemstone jewelry, such as blue agate jewelry, because of their beauty.