Glass crackle beads in the Hogwarts House colors. Subtle and lovely way to show your House pride.
Colors per Pottermore:
"The four Hogwarts houses have a loose association with the four elements, and their colours were chosen accordingly. Gryffindor (red and gold) is connected to fire; Slytherin (green and silver) to water; Hufflepuff (yellow and black, representing wheat and soil) to earth; and Ravenclaw (blue and bronze; sky and eagle feathers) to air."
Glass and metal beads
Nickel free alloy ear wires