You first need to understand '말' is not for the meaning of 'word' or 'horse'. In this sentence, '말' is used as a quantity unit which has been used for a long time ago in Korea.
One '말' is same as about 18 L.
and the mean of '이라도' is similar to your thought; 'even though' ( actually it is a totally new part of word class which is used in Korean but not in English)
So, the sentence means directly that 'even though one has three '말'( 54 L) of pearls(beads), they are valued when in chains.'