10.5" Imari Plate x4

My grandmother use to own (or manage?) an Oriental Bazaar in Atlanta. When it closed down in the 90's, all of the inventory ended up in her basement. I have now come into possession of 4 10.5" Imari plates.

I have tried to look them up, but the ones I have found have some differences; i.e. the feathers around the hourglass shape are blue on mine, whereas they are grey on others. The stamp on the back has different characters than the ones I have seen online, or the online ones have crown on the back and no characters.

Based off of what I have found regarding "Made in Macau," it looks like they were made in the 60's or 70's, but I'm failing to find out more.

[It only allowed me to upload pictures under 1MB despite saying it could be 7MB per picture. So I do have better quality pictures available]