I do not agree with Jamey's opinion that "the Boshan industry developed too late to have much or any effect upon the Manchu costume." Over the last 40 years or so, I have examined more than one hundred authentic Mandarin Court Necklaces, since buying and selling antique Chinese beads has been one of my specialties. I have observed that about half of the MCNs I have handled were made of glass beads. And therefore I reached the conclusion that a significant percentage of Mandarin Court Necklaces made during the Ching Dynasty were either made of glass or, at least, included some glass components. Glass was an inexpensive way to fulfill the color requirements indicating rank of the official wearing the necklace, as compared to coral, ivory, or semi-precious stones.
I am also certain that the MCNs with glass beads and components that I examined were not recent fakes. I became familiar with the parts and construction of authentic pieces by taking many of them apart.
Another piece of evidence supporting the use of Boshan glass in MCNs is the use of glass beads for the finials on Mandarin hats. The finials can be studied much more easily than MCNs since they have metal fittings that can be easily examined for their age appropriate construction and patina. Finials were made to coordinate with the necklaces, supporting a conclusion that glass was commonly used for MCNs.
Note: MCNs typically date from 1644 to 1912 (Ching Dynasty). Boshan glass dates from the 14th century, with Boshan glass beads especially coming into use in the 18th century under Qian Long (1736-1796). For more information see: "Chinese Glass Beads: New Evidence", by Peter Francis (www.thebeadsite.com/be02-ch.htm)…link courtesy of Rosanna.
Robert Liu's article: http://static1.squarespace.com/static/54a8ea9ae4b0d1cd06f46bba/t/54e524efe4b0bc89fe275d35/1424303343507/Orn36_4_ChineseGlassBeads.pdf