I am not impressed, they could cut 1000% by using: big bawl, pipe, simple mechanical sorting mechanism, and electronic counter.
I had this video in mind: https://youtu.be/nu7snTgSFeE?t=39 They do not look they are gentle with them.
Described method has repetitive manual steps: - put pearls in the trey, - take a photo - take out pearls, - put new ones ...
These steps do not look like much, but if we are talking about amount shown in video can be hundreds of hours.
Phone costs money, and making application costs developer's time and money (so nothing is free) ...
Counting device can be made by Lego, so very cheaply, here is simplistic example: https://www.youtube.com/watch?v=9YguSl_IekQ
Of course device should be made having in mind handling.
By the way application probably has a lot of sense for small dealers, or jewelries,