。
She especially loved polishing jewelry.
Literal
She [topic-は] above all jewelry [object-を] polish [nominalizer-の] [subject-が] liked-was.
のが好き — the nominalizer の turns the verb 磨く into a noun-like 'the polishing of jewelry,' and が marks that activity as the thing she likes. This (verb + のが好き) is the standard frame for 'like doing X.' とりわけ adds 'above all else' emphasis, slightly more literary than the everyday 特に.