These are crystals stones that are said to be of particular benefit to and/or are associated with those born under each sign of the zodiac in western astrology.
These associated crystals are often preferred by people of the related astrological sign. Sometimes, though, they aren’t at all. This can be due to the fact that one’s astrological sign is really just one portion, generally the Sun sign, of their entire astrological chart. Other factors in their individual chart may mean that they prefer and go well with other stones altogether. The stones shown for a particular sign can be placed on their associated chakras, worn, or carried.
Because a stone is listed as related to or benefitting a particular sign, doesn’t mean it’s the only crystals that will be a benefit, or that they anyone has to use it. As with all things, trust your higher self above all.