Lady's Freshwater Pearl Convertible Necklace. Pearl Size: 9.5-10mm. Necklace Length: 34" Inches (Separates into 16" and 18" Segments.) An extremely high-quality strand of cultured freshwater pearls strung in a most unusual manner. In the strand, there are two sets of two pearls that actually unscrew, but the joining is invisible (see pictures below). From this one strand, by simply unscrewing the necklace in two different areas, it will convert to an 18-inch and a 16-inch strand. Of course, all of this is seemless when it is properly put together. Of course, there isn't a glitzy clasp, but there are pearl necklace enhancers if you want to glitz it up a bit. The entire strand has pearl of the important 9.5 to 10mm size. At that size, they have to sit in the oyster for a very long time to get formed and therefore they are generally very expensive.