Several people have emailed me about my biggest piece of Mersea sea glass, and I can confirm that it's definitely a Rose's Lime Juice bottle, at least 100 years old, and would once have looked like this.
My original pic was slightly disingenuous (sorry) because the bottle was actually found half-buried in mud, not sand - the photo was taken after it had been cleaned up. Most of its opacity will have been caused by the high pH of the sea-water rather than by the abrasive action of the waves, hence the slight iridescence and the relatively sharp edge at what remains of the neck.
It's currently in use as a vase on the kitchen windowsill - here it is with some random bits from the garden (nothing like such an impressive display as these sweetpeas, though).
2 days ago