Gallery of Collar/Necklace styles
The Duras sisters first appeared in "Redemption l & ll, Star Trek: Next Gen."  Their costumes were highlighted with bright red sleeves, cut down chestprotectors, and lots of cleavage.  The collars were both modifications of the basic collar.  They both had pewter accents (badges).  Lursa's was cut down to accommodate her badge and little else.  Betor's was more traditional in shape, but the tubing and color were unusual.
When their 'look' was updated for "Generations" colors were changed and so were the accents.
General Chang from "Undiscovered Country" had a plasticy collar with a pewter accent.  With the advent of the film, the Klingon Empire got the new shiny plastic Michelin Tire Man look.  The costumes are still used.  The most recent exposure was on the "Barge of the Dead".  Considering how old and long ago the Captain of the barge was consigned to this duty, it was pretty unlikely that he would be wearing parts of that uniform.  B'Elanna's costume had many elements of the Undiscovered Country uniforms.   Her collar was like that of Chang.  It was basically flat with glossy tubing.  Although it has some of the same cut lines, it is flatter then the one used from Star Trek The Motion Picture onwards.
There are various examples of embellishments from various characters.  Grilka's collar was embellished with the same trim as that used on her costume.  It was applied to the upstanding collar.  "The House of Quark" DS9
The most elaborate collar was worn by Sirrela in "You are Cordially Invited"  The collar supports the long dangling pendant, and the two metal pieces on her shoulder reminiscent or those found on the chestprotector, have to support alot of weight.  She claims to be descendant of the Emperor, hence the elaborate collar and crown.
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