The pictures below show the design for a Sterling Silver Pendent Holder (the item with the Black stone is a Pendent, and is not part of the Holder) that will convert your collar into a nice necklace. Perfect for giving that little extra glamour to your neck when you want it.
As can be seen by the photos, this particular holder slides over one of the ends of the collar and remains hooked in place. This device is made for a particular size collar. One-Size does NOT fit all.
Price for this little guy is as follows:
For 6mm collars = $4.00
For 8mm, 12mm, and Pattern Wire collars = $5.00
***I have a similar version that you can add without undoing the collar.