If I happen to count how many rhinestones are in the bag will there be exactly 1440 rhinestones if I order ss16... the bag looks small in pictures

So did you buy the ss16 bag and COUNT THEM? having built a career as a seed scientist where often I was stuck counting hundreds and even thousands of itty seeds larger and smaller than ss16's to be assured I know how to quickly count. I also know the there is value in counting and value in not bothering. So it's up to you. If you can count in 5's quickly go for it. Otherwise these are done by weight and I suspect like in the seed industry weight is usually a little over expectation. However if done via an appliance that uses a technique to gravity shaking them up a counting machine those are notoriously off their count either direction under or over. So I think most buyers aren't into counting. Even with my experience and occasional anal tendencies I'm not going to bother with this type of product. If however I get a bag and know from experience that it appears way too short or there's a hole in the bag and perhaps many have been lost along it's route to me I would speak up but only after I count and clarify it's short by a substantial #. A few off one way or the other it's fine. You either have some degree of trust or NOT. Read the negative reviews to see what the theme of the complaints are if there are any. And that usually will give you this kind of answer right away.

are the rinestones 6mm

The size as below: SS3 1.3-1.4mm, SS4 1.5-1.6mm , SS6 1.9-2.0mm , SS8 2.3-2.5mm, SS10 2.7-2.8mm ,SS12 2.9-3.0mm ,SS16 3.9-4.0mm, SS20 4.6-4.8mm, SS30 6.4-6.6mm, SS34 7.1-7.3mm, SS40 8.4-8.7mm. Please choose size SS30 which is most close to 6mm.