The irish inticrate patterning, used in illuminated books or sculpture, has it´s roots in ancient celtic and anglo-saxon art. The so-called "Insular Art" was created by influence of Chritianity. The Insular Art reaches it´s peak in complex patterns of knots and tridents at the early middle-ages. In monastaries lavish illuminated bible and gospel-books were painted, beiing decorated with inticrate patterns. The most famous examples are the the Book of Dorrow, The Book of Kells or the Gospels of Lindisfarne.
This Earrings in Insular Art style were made from 925 silver, with findings in jeweller quality (nickel-free).