Questions & Answers about Smycket som vi köpte är mycket värdefullt.
How can we tell that som is acting as the object here?
You can tell by looking at what comes right after it. Since the subject vi (we) immediately follows som, it means som is receiving the action of the verb köpte (bought). If som were the subject, a verb would come right after it instead.
Why does the translation say "piece of jewelry" instead of just "jewelry"?
In English, "jewelry" is an uncountable noun (you can't say "one jewelry"). But in Swedish, ett smycke is a regular countable noun that means a single piece or item of jewelry. Adding the definite suffix -t makes it smycket (the piece of jewelry).
Why does värdefullt end in a -t?
Adjectives need to match the gender of the noun they describe. Because it is ett smycke (an ett word), the adjective värdefull (valuable) must take the -t ending to become värdefullt.
Does the long som clause change the word order of the main sentence?