the ridges between the flutes do look sharpish, which might indicate cutting. As a guide to determine if the flutes were cut or pressed, look at them with a low power lens - and if cut you should see feint remains of the grinding marks - the scratches will run at 90 degrees to the long axis of the tumbler. Again, you may be lucky and see feint scratches within the pontil depression - assuming it really was detached from a pontil rod.
If the tumbler was shaped by pressing you might find mould seams somewhere on the body, but quality pieces were often fire polished to remove the seams. Another trait of pressed moulding is that often the molten glass didn't always fill the extremities of the mould perfectly, and small imperfections remain on the outer surface of the glass - tiny hair-like defects which might be a centimetre long or less.
Small stones more often do appear white (rather than black) - and might indicate an early to mid C19 date. However, a little caution, as small bubbles might be mistaken for genuine stones.
The 'ring' will depend to some extent on the thickness of the glass - less ring for a thicker glass.
Regret I still can't see the base clearly - does the tumbler sit on a flat base - from the depression to the outer edge?
Flip glasses/tumblers seem to be a States thing - there is little in the books that I can see here, although the indication is that 'flip beakers' as they are sometimes known are usually considered to fall within a height range of 14 - 17 cms. (c. 5.5" - 7"), which is taller than your example, and larger ones apparently had a cover of sorts. Genuine flips seem to have been made during the C18 and C19.
It's quite possible that you have an attractive tumbler rather than a purpose made flip, and sufficient wear might still date this to the first half of the C19, which makes this an interesting piece.
I guess there are people your side who will know far more about these things than us limeys
