The clavicle piercing (also collarbone piercing) is stitched in the part of the collarbone.
In fact more precisely along under the collarbone. It´s very precarious to stitch this piercing, because there are important native vessels (artery and vein) at this part of the body. If any, this piercing should be stitched by a really experienced piercer.
If it was stitched correct and afterwards it´s carried very well the healing time takes about 2 to 6 months. Certainly it also can takes up to one year.
For jewellery a very long curved barbell is applied. Let you consult of your piercer explicitly before you decide.