<P> The triquetra has been found on runestones in Northern Europe and on early Germanic coins . It presumably had pagan religious meaning and it bears a resemblance to the valknut, a symbol associated with Odin . </P> <P> The symbol has been used in Christian tradition as a sign of the Trinity (Father, Son and Holy Spirit), especially since the Celtic revival of the 19th century . When modern designers began to display the triquetra as a stand - alone design, it recalled the three - leafed shamrock which was similarly offered as a Trinity symbol by Saint Patrick . have also suggested that the triquetra has a similarity to the Christian Ιχθυς symbol . The triquetra has been used extensively on Christian sculpture, vestments, book arts and stained glass . It has been used on the title page and binding of some editions of the New King James Version . </P> <P> A very common representation of the symbol is with a circle that goes through the three interconnected loops of the triquetra . The circle emphasises the unity of the whole combination of three forces . It is also said to symbolise God's love around the Holy Trinity . </P> <P> In contemporary Ireland, it is traditional for lovers to exchange jewelry such as a necklace or rings signifying their affection . The triquetra, also known as a "trinity knot", is often found as a design element is popular Irish jewelry such as claddaghs and other wedding or engagement rings . </P>

What is the symbol on the necklace in constantine