regret to say the very few pieces of m.g. I once owned, have now gone, so will have to buy one or two examples as a reference guide. The memorable makers were States factories - Fenton and Westmoreland for example - though many others that side produced the stuff. I did once have a book on m.g. but that went too - am sure it was made here as well. I think it's true of most pieces/colours that there's a noticeable translucent appearance with an underlying milky or opalescent presence, and although there are collectors who include opaque Sowerby colours under this heading, there is a difference between their Vitro-Porcelain and true milk glass. There was a product from Sowerby called 'Blance-de-lait' which, despite the name, isn't milk glass either.
In view of the silence, perhaps no one here collects the stuff.