I agree, Keep them as a set. They have a super clasp, those stones have beauty value regardless of what they are. But, if you can get a GIA trained jeweler to look at them, the price would be higher if the gems are untreated rubies. If they are spinel, it doesn't matter for looks, but people do like to know what they are paying for. That clasp is what makes your pearls stand out.
Also, as Karin advises, comb those sold listings. It is a real education in what people will pay, and some days it is much better than others, though I don't have a clue why. Please keep us informed of what you learn. Good luck!