Rosanna,
I will do my best on your images. The nugget looks like low grade turquoise that has been treated with dyed resin or maybe just dyed. The melon bead leaves me clueless in regards as to what type of stone may have been used but as you can see it has been dyed and coated with some type of resin. It is not howlite because howlite is the same hardness through out and this stone is not.

Looking at the round bead its obvious that the Chinese have a blue resin that they will put on most anything and if it looks like turquoise they make beads and put the resin on them. The disk bead looks like it was made with feldspar which is very common planet wide, again I would say they have dyed it.

The pillow bead is either low grade treated turquoise (don't think so)or again dyed feldspar.

If you take a heat source like a bic lighter and hold a piece of each stone near the edge of the flame for five or ten seconds then smell the stone more than likely you will smell plastic on every one of them.

I used to work with one of the largest opal dealers out of Australia and would cringe every time he would get his nippers out to clip the edge of his rough, some of the rough being 2000 an ounce, so he could grade it. I have a pair of the nippers and use them for clipping stone of any and all types. If you can get Japanese made nippers with carbide inserts ........... Much better than a hammer and much less destructive.

All my best ....... Danny