thank you for writing in. Initials on a ring which are difficult to identify, as the letters are so stylish or entwined are called decorative monograms. The blog post Monogram in the Stratocracy" goes into monogram and rings in more detail. Decorative monogram rings became popular in the 18th century. Some of the 18th century monogrammed rings would feature the actual inscribed monogram in rose cut diamonds.
White gold on the other hand, relatively speaking is more "modern" and was popular in the 1920s, when white gold was introduced as a precious white metal alternative to the more expensive platinum, which is also "white" and a lot harder to work with.
The weight of the ring is important to consider and in relation to values, please see Expert Appraisals.