So, I read the bit on amber in John Clarke’s ‘Jewellery of Tibet and the Himalayas’. It’s on Page 38.

The bits relevant to our discussion are: “From the early seventeenth century, the more distant Baltic amber was also brought to Indian ports by European trading companies .… other supplies of Siberian amber, from the shores of Lake Baikal in Buriatia, part of eastern Siberia lying on the borders of Outer Monglia, were being used by the nomads of north-east Tibet in the 1940s. Pale yellow Russian amber which may be from the same source is being imported into eastern Tibet [Kham] today.”
(my emphasis)

Two pages earlier, there is a photograph from the Yushu festival 2003 showing none other than the woman in the pictures below. (In the book it’s a sharper, frontal photo, and she has her eyes closed)

The caption reads “Woman wearing Gaba head ornaments: A festival headdress showing the extraordinarily large amber pieces set with coral worn in the north-easterly part of Kham. Sewn onto felt strips these extend most of the length of her back. The necklaces of mixed coral and imitation dzi beads are also definitely for wear on special occasions.”