From Wellcome's Ancient Cymric Medicine

The most striking adornment of the Arch~Druid was the iodhan moran, or the breastplate of judgement, which possesed the mysterious power of strangling any who made an untrue statement while wearing it. Godfrey Higgens states that this breastplate was put on the necks of witnesses to test the veracity of their evidence. The Druid tiara or angulum, its front embossed with a number of points to represent the sun's rays, indicated that the priest was the personification of the rising sun. On the front of his belt the Arch~Druid wore the liath meisicith_amagic brooch, or buckle, in thecenter of which was a large white stone. To this was attributed the power of drawing the fire of the gods down from heaven at the priest's command. This specially cut stone was a burning glass by which the sun's rays were concentrated to light the alter fire. The Druids also had other symbolic implements, such as a special shaped golden sickle with which the cut the mistletoe from the oak, and the corman or sceptor, in the form of a cresent, symbolic of the sixth day of the increasing moon. Admission to the midnight cerimonies was gained by means of a glass boat called Cwrwg Gwydin. This boat symbolized the moon which floating among the waters of eternity, preserved the seeds of living creatures within its boatlike cresent.