Many jewelry markings on Antique Jewelry and Costume Jewelry are in the form of script handwriting. The problem is there are many different forms of script writing. For example, there's Italian cursive, Russian cursive, Cyrillic cursive, a Russian style of writing with cursive characters, cursive Roman, cursive Greek and the list goes on..

English cursive, is no doubt the cursive inscribed on the ring, you are referring too. You can compare the form of the letter on the jewelry with the Script writing board in the Jewelry Resources here.

English cursive can be in upper or lower case. Italic is different to cursive again. After the 1960s, it was argued that the teaching of cursive writing was more difficult than it needed to be.

Simply slanted characters, termed italic, were considered by some to be easier and traditional cursive unnecessary. Even within English cursive there are different styles and variations within the cursive family. Basically without a photo it is difficult to tell.

It's also important to know exactly if the shape around the letter is an oval or a circle. It might seem a small thing but can make a big difference in a determination.

I did discover an early 20th century - L in a CIRCLE in my research (The Jeweler's Index, 1922 edition) but it's in the style of a Times New Roman font which is a serif typeface commissioned by the British newspaper, The Times, in 1931.

Reference:
http://en.wikipedia.org/wiki/Times_Roman