Most hardware is named for what it does. The lobster clasp is named for what it looks like, and the resemblance to a claw is close enough that the name has required no explanation in any language that adopted it.
Stone Story
Ruby registers 9 on the Mohs scale, second only to diamond in hardness among natural gemstones. For a July birthstone gift intended for daily wear, that durability matters: ruby is suited to rings and bracelets that will actually be worn rather than reserved for occasions. The practical quality matches the historical status.
Quality & Value
The rarity of large gem-quality rubies reflects the geological conditions required for their formation. Fine color requires specific chromium concentration; large size requires crystal growth conditions that rarely coexist with fine color. Fine rubies above five carats are documented as rarer than equivalent diamonds by volume; stones above ten carats in top color are sufficiently uncommon that individual specimens achieve auction records that price the near-impossibility of their geological origin.