The necklace appears to be to be a very pretty strand of akoya pearls, well matched and lustrous. It's hard to say from the photos if the earrings are also akoya as many ladies by imitation pearl earrings, but if there is a metal mark indicating they are karat gold then they are likely akoyas also.
As they belonged to your grandmother, surely their greatest value is sentimental! However, you are looking for a dollar amount, which we can't give you as we don't do appraisals. I will say that replacement value (for insurance purposes) is higher than resale value.
You can get an idea of what replacement value would be by looking at what similar necklaces are selling for online or in stores.
And as for resale value, you can check eBay for what similar necklaces have sold for recently. Unfortunately pre-owned pearls do not tend to hold their value unless they were owned by someone famous or are a famous brand (Mikimoto in particular).
They are lovely and hopefully you would enjoy wearing them.