She's the apple of Jim's eye, the jewel in his Patusan crown, the love of his life (okay, that might be pushing it; the love of his life is totally the sea). Great. But who is she? Like many of Conrad's characters, the real Jewel is elusive. We know that she is the daughter of a Dutch-Malay woman, and that her stepfather is Cornelius, the man everyone loves to hate. Aside from these concrete facts, Jewel's character is a study in contrasts.
On the one hand, she plays the love interest role, nothing more. But on the other hand, there's a darker side to Jewel, one that Marlow inadvertently reveals in passing:
He swore he would never leave me, when we stood there alone! He swore to me!" [...] "And is it possible that you – you! do not believe him?" I asked, sincerely reproachful, genuinely shocked. Why couldn't she believe? Wherefore this craving for incertitude, this clinging to fear, as if incertitude and fear had been the safeguards of her love. It was monstrous. (33.6)
No, Jewel isn't your average starry-eyed lover who swoons for the dashing lead. In fact, she might not even believe in Jim. She craves incertitude and clings to fear. She's capable of monstrous feelings. The world has done her wrong, it seems, and she has her guard up.
She's both a victim and a kick-butt female. Marlow tells us, "I would have given anything for the power to soothe her frail soul, tormenting itself in its invincible ignorance like a small bird beating about the cruel wires of a cage." (33.13) He sees her as trapped, frail, and tormented.
In this moment, Marlow seems to forget that Jewel is also quite capable of rescuing herself. She might be less trapped than he thinks. After all, she is the one who saves Jim from a group of assassins:
She was holding a dammar torch at arm's-length aloft, and in a persistent, urgent monotone she was repeating "Get up! Get up! Get up!"
Suddenly he leaped to his feet; at once she put into his hand a revolver [...] (31.3)
Way to take charge, Jewel. If she hadn't stepped in here, Jim probably would have died several chapters before the end, and then where would we be? She is surprisingly stubborn, but she is also quite vulnerable. In short, she is full of contradictions, and this is not lost on Marlow, who tells us, "She was audacious and shrinking. She feared nothing, but she was checked by the profound incertitude and the extreme strangeness – a brave person groping in the dark." (32.19)
That dark is a world controlled by men. For much of her life, Jewel has been at the mercy of Cornelius, her wicked stepfather. At the end of the novel, her happiness is hitched to Jim's star, and we all know how that goes. In this particular era, men controlled the lives and destinies of women, and Jewel's example is no different. She may survive Jim and escape Patusan, but in the end she seems lost in her painful memories, a victim of circumstances and her own dark thoughts.