Rings

I have a morbid fear of these my ancient rings.
Have I not found subtle poison in many a gem?
This serpent, see how abominably he stings!
This opal that I love, more for its intricate flame
Than for its changing colours, shoots forth fires;
This paler sapphire, Cesare Borgia's ring
That hid the translucent poison of desires
That eat one up beyond imagining:
Of these I endure the intolerable agonies.
Some die of them, some say, but I say no.
The spirit has more tenebrous maladies
Then the hard-hearted hearts of witches know.
Of certain stones I am hallucinated.
The Devil's in me; and my intense luxury
Stings me like ardent fires that stir the dead:
Shall all these evil visions be the end of me?