Regarding the pearls in post #8, when you photograph them, please use a plain white background without flash.
We should assess whether they may be imitation. They seem rather uniform and the knots seem rather large for real pearls. Real pearls have small drill holes as they are sold by weight and small holes preserve weight; fake pearls often have larger drill holes, necessitating thicker thread and larger knots. This is not always the case, however, with better fakes (e.g. Majorica imitation pearls have small drill holes.) Also, it is more common for imitation strands to be strung without a clasp.
• Before handling them much, hold this strand against your face or lips (which are very temperature sensitive), and then hold the freshwater strand against your face or lips. Real pearls feel cooler than glass imitation pearls.
• Rub 2 of the pearls together gently, or rub one gently against the edge of your front tooth. Real nacre feels a bit gritty; fake pearls feel smooth.
• Check around the drill holes. Imitation strands may have swirls of excess coating, near the drill holes. The better fakes may not, however. There may also be some flaking off of the coating near drill holes, with older fake strands.
• Please take close up photos of any flaws or other unusual surface characteristics. If the nacre is missing anywhere, get a shot of that.
• If you have a loupe (a 10x magnifier) look at the surface and compare what you see with a smooth part of the surface of the freshwater strand. Real nacre is very smooth-looking at 10x magnification, while imitation pearl coating looks coarser.
Also, please measure the length of the strand, doubled.