Amethyst is a gemstone believed to have occult properties, described by sixteenth-century writer Camillus Leonardus as "reckoned among the purple and transparent stones, mixed with a violet color, emitting rosy sparkles." The Indian variety is the most precious. When made into drinking cups or bound on the navel, it was claimed to prevent drunkenness. It was also believed to sharpen the wit, turn away evil thoughts, and give a knowledge of the future in dreams. Drunk in a potion, it was thought to expel poison and render the barren fruitful. In ancient times it was frequently engraved with the head of Bacchus and was a favorite with Roman women.
The Greek word "amethystos" may be translated as "not drunken", from Greek a-, not + methustos, intoxicated. Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were often carved from it. In Greek mythology, Dionysus, the god of intoxication, and wine, was pursuing a maiden named Amethystos, who refused his affections. Amethystos prayed to the gods to remain chaste, which the goddess Artemis granted and transformed her into a white stone. Humbled by Amethystos's desire to remain chaste, Dionysus poured wine over the stone as an offering, dyeing the crystals purple.
Variations of the story include that Dionysus had been insulted by a mortal and swore to slay the next mortal who crossed his path, creating fierce tigers to carry out his wrath. The mortal turned out to be a beautiful young woman, Amethystos, who was on her way to pay tribute to Artemis (the hunter goddess). Her life is spared by Artemis, who transformed the maiden into a statue of pure crystalline quartz to protect her from the brutal claws. Dionysus wept tears of wine in remorse for his action at the sight of the beautiful statue. The god's tears then stained the quartz purple. Another variation involves the titan Rhea presenting Dionysus with the amethyst stone to preserve the wine-drinker's sanity.
Therefore, a drinking society would be offended by what it represented. The length of necklace would be however long it needs to be to reach your heart of just above it.