When does an X become a cross?

When it is turned vertical . . . the odd enamel and encrusted gemstone helps!

Lothar Cross - (about the year 1000). National Museum of Ireland.

British Museum - Byzantine Gold Pectoral Crosses (and Reliquary).

Irish - Cross of Cong: A processional cross of oak covered with bronze plates decorated with panels of gold and gilt bronze interlacing and gold studs. Made around 1123 AD to the order of the High king Turlough O'Connor to enshrine a relic of the 'true cross' and was kept at Tuam, Co. Galway.