Vintage Mexican sterling silver beads, used for making Mexican silver bead necklaces in the 40s and 50s.  The necklaces were called silver pearls and strung on silver chain.  These are very old and have varying amounts of oxidation from age.    They shine up easily.    Stringing holes are 1.5-2mm depending on the size of the bead.  These beads are wonderfully versatile.  Available in sizes from 5mm to 14mm.