From the manufacturer:
made of high-quality alloy and adorned with sparkling rhinestones. The small cross has luster, does not fade, does not rust, and is suitable for long-term wear or use
UNIQUE DESIGN: These Cross Charms feature a classic and exquisite design, with sparkling rhinestones adding a touch of elegance and glamour. The intricate details of the crosses make them stand out and add a unique touch to your jewelry creations. The high-quality materials ensure that the charms are durable and long-lasting.
String is long-lasting black or white stretch string.