Field describes a 222-pearl necklace with a ruby clasp. Meylan lists a four-row pearl necklace of 55, 55, 56 and 56 pearls (which equals 222). Both state Punjab was the source of the pearls. Menkes lists 'Four strand pearls from treasury at Lahore . . . with ruby snap' and also says they were reset in 1941.
So perhaps the two strands with ruby clasp worn to Covent Garden could be half of the Indian pearls with the longer strand being part of the lot as well.
Whatever the source, here are photos of the Queen wearing a double strand pearl necklace which is neither the Queen Anne/Queen Caroline pearls nor the Hanoverian pearls.
Note that at the Festival of Remembrance HM also wore the necklace with the ruby earrings.
The bottom strand of the double rows have tiny pearls alternating with the larger ones toward the back.
However I'm not certain this a ruby clasp or something else.