This is the oldest reliquary of Saint Catherine preserved in Sinai, and consists of a rectangular base, with a hemispherical depression at the bottom, and a triangular prism lid. It is adorned with floral motifs carved in relief on the two long sides; the relief sculptor employed a drill to achieve the depth of the relief decoration. The motif is made up of acanthus leaves springing out of long stems that envelop rosettes containing lotus flowers. Both other sides are decorated with a cross surrounded by plant leaves carved in low relief. The side bears a large, double cross of the Byzantine “Anastasis” type, and the other a small, simple cross. The same low relief technique was applied on the simplified, winding floral motif on the lid; these motifs terminate in half-palmettes on an unadorned background. Νeither the place nor the date of construction of the reliquary, nor the date of its acquisition by the monastery are documented.
Nevertheless the style of the decorative motifs and the technique of their execution associate the reliquary casket with sculptural works produced in the Latin kingdom of Jerusalem during the last decades before its dissolution in 1187. Modern research has pointed out that the reliquary was resting on the sixth century chancel panel and on other sculpture specially made in the very end of the twelfth century which parallel art found in the Holy Land. The combination of elements of both Byzantine and Western styles can only be compared to the “Crusader” group of icons preserved in the monastery of Sinai.
The reliquary of Saint Catherine is first reported to be in the Katholikon in a 1214 manuscript containing the typicon rules of the monastery of Sinai; around the year 1480 it is reported that metal padlocks were added for extra security. Its first depiction which dates to the sixteenth century was created by a Western pilgrim, Fra Noe Bianco. The reliquary appears to have resided permanently inside the Katholikon of the Sinai Monastery for about six hundred years, until the late eighteenth century, when it was replaced by a new one, kept under a ciborium, preserved to this day in the bema area of the Katholikon.