Opal is the traditional birthstone for October, and tourmaline is the month's other officially recognized stone. Anyone shopping for opal jewelry is really shopping for a gem defined by one trait above all others: a shifting flash of color that no two stones share in quite the same way. That shifting color effect gives opal its identity, and it also makes buying opal jewelry more complicated than buying most other gemstones. This guide explains what creates that effect, how the major opal...

Sapphire sits at 9 on the Mohs hardness scale, second only to diamond among gems worn every day. That durability, paired with a color range most shoppers underestimate, is why sapphire has represented September births for generations. September birthstone jewelry covers far more than a dark blue ring: sapphire is a variety of corundum, the same mineral species as ruby, and it occurs naturally in almost every color except red. Shoppers researching sapphire birthstone jewelry usually want two...

Learn how rhodium plating protects jewelry from tarnish, what it costs, how long it lasts, and how to care for rhodium plated jewelry.