I have not been able to find much information on the jewels of the Duchesses of Hamilton. In part this is because several successive Duchesses have been more interested in country pursuits than attending society functions where they might have been photographed.
The other factor limiting a full exploration of the family jewels is that Lady Mary Hamilton (later Duchess of Montrose) was the sole heiress of her father and mother. Her father, was the 12 Duke of Hamilton and her mother a daughter of the 7th Duke of Manchester and Louise, Duchess of Manchester and later Duchess of Devonshire, known as the Double Duchess. A lot of the Duke's property was left to his sole offspring, Lady Mary, later Duchess of Montrose. In many reports she was described as the greatest heiress of her age.
After the death of the 12 Duke of Hamilton in 1895 the title passed to a distant cousin.
So far I have no idea if any jewels were entailed either to the holder of the title or specific estates.
Mary, the widow of the 12th Duke of Hamilton later remarried, but continued to use her title of Duchess of Hamilton (as was then a common practice). Some indication of the quality of her jewels can be gained from this 1909 published item.
The wife of the 13th Duke of Hamilton (Nina Poore) was a leading campaigner for animal rights and rarely appeared in the social columns and even more rarely wearing grand jewels.
The 13th Duchess in 1908 wearing an attractive necklace.
Dressed for the 1937 coronation
Of Nina, Duchess of Hamilton's daughters-in-law only one wore the family tiara. The others wore non jewel headdresses.
This was the wife of the second son who inherited the earldom of Selkirk. (This earldom had some very different rules of inheritance reserved in normal times for the second son of the Duke)
Elizabeth Percy, 14th Duchess of Hamilton wearing the tiara in 1955 at a soiree given for the Shah and Queen Soraya of Iran in 1955