Sagacia’s Statement Ammolite Earring Although gem-grade ammolite is very rare, it is considered a semi-precious gemstone. It is similar to biogenic gems (biogenic gemstones are those gemstones formed by living organisms) such as pearls. The most common shape of the shell of ammolite is similar to a ram’s horn. Perhaps, this is why this stone is the zodiac stone for Aries (the Zodiac possessing the ram sign). On top of this, Egyptian astrology linked Aries with the sun god Ammon, which they depicted in the form of a human body with a ram’s horns.