There's a clear ambiguity on the text regarding the jewelry and the messages.
The narrator is talking about how it was made jewelry with the father's message with Morse code but the phrase is as follows:
"[...] with Dad's messages - a necklace, an anklet, some dangly earrings, a tiara - but the bracelet was definitely the most beautiful, probably because it was the last"
You cannot say for sure if the last that is referred on the text is that the last message or if it is because it's the last jewelry.
It can either be the last message that makes it to be the most precious or because it was the last jewelry made. The pronoun "IT" can be referring to either.
That is the ambiguity