How nice to have received a gift of pearls from your mother!
Those are cultured freshwater pearls from China. They don't have any bead inside to make them round, so they grew in that eggy shape. That means they are solid nacre and very durable. That is also a natural color for freshwater pearls.
JCM is the mark of Jacmel Jewelry Inc.
https://trademarks.justia.com/863/70/jcm-86370827.html
The primary value of these pearls is their
sentimental value.
Resale value will not be high
. Aside from the fact that pre-owned pearls in general don't tend to hold their value (except for historic pearls or brand name pearls like Mikimoto), the Chinese pearl industry has improved its techniques in the past 20 years, and rounder / larger pearls are now being produced. The market prefers round pearls. These egg shaped pearls are not as desirable to today's buyer. Sometimes the clasp is the most valuable part, given the high price of gold these days.
However, if you are considering selling them, you can get an idea of what you might get for them by looking a SOLD listings for pearls similar to yours on eBay. (Listing price is not helpful here; the relevant number is what people have actually paid for them).