Price, for one! The Japanese pearls are costlier!
I am by no means any sort of expert on Kasumi pearls, but I would not expect to see a silver clasp on a strand of genuine Japanese Kasumi pearls, because of their price.
Also, I have actually seen strands not very different from the strand in your photo at T. J. Maxx, a discounter store in the USA. (That store does not carry higher end pearls.)
From what I've seen the Japanese ones are generally more colorful, also, although some vendors have very nice Chinese ripples that resemble the Japanese Kasumi pearls. Kojima has been mentioned. They sell (or have sold) both.
Here is a recent thread with some great photos:
I was looking at the Kasumi pearls on @kojimapearl's website . I have never seen one in person and up to recently, I didn't know they existed. I just wanted to know what criteria is used when buying one for oneself? There are so many kinds: some smooth , some deeply rippled, some pastel, some...
www.pearl-guide.com
Here is an older thread you may wish to read...
Sorry if this has been asked a million times but I've tried going back over old threads and haven't seen a lot of information about these two pearls. Can someone give me more information? I know the Kasumi comes from only ONE lake (hence the name of course) and I think there are only three...
www.pearl-guide.com
I did a quick search for threads on PG with "Kasumi" in the title and came up with these search results:
www.pearl-guide.com