In Romeo and Juliet, what is the purpose of Romeo's line to Balthasar in Act 5 Scene 3 lines 30 - 32?:"But chiefly to take thence from her dead finger/A precious ring - a ring that I must use/In dear employment."
In Act V, Scene 3, Romeo has procured poison from the apothecary and with Balthasar he approaches the tomb of Juliet. But, he instructs Balthasar to wait outside the tomb for him and lie under a nearby yew tree and listen for the approach of anyone. If someone comes, Balthasar is told to whistle to Romeo.
As his reason for entering the tomb of Juliet, Romeo tells him that there is a ring on Juliet's finger which he must remove; this ring is Juliet's wedding ring since Romeo may wish to hide from the Capulets the fact that he and Juliet were married, although it seems improbable that Lady Capulet and her husband or their servants did not notice this ring when they prepared her for the tomb or as she was buried. Thus, it seems more likely that Romeo simply wishes to keep Balthasar at a distance so that his servant will not suspect him of wishing to commit suicide and prevent him from doing so.
The time and my intents are savage-wild,
More fierce and more inexorable far
Than empty tigers or the roaring sea. (5.3.47-50)
There is certainly a sense of fate in Romeo who warns his servant that he is not to enter Juliet's tomb. By removing Juliet's ring, Romeo sets her spirit free: "A ring that I must use in dear employment..."
Furthermore, he does wish to have Balthasar stand guard lest anyone else come along and discover that he has entered the tomb illegallly, for he would be subject to severe punishment if caught. (Remember that Friar Laurence runs quickly when he hears the approach of the guards for this same reason.)
It is very important to remember the context of these lines. Romeo is approaching the tomb where Juliet's body is placed with the intention of killing himself. However he is with his servant, Balthasar, who is obviously not going to let his master do what he intends. Therefore he needs to come up with a plausible excuse in order to deceive Balthasar and try to convince him that he is not going to do any harm to himself. This is why he tries to give a reason for his actions:
Why I descend into this bed of death,
Is partly to behold my lady's face;
But chiefly to take thence from her dead finger
A precious ring, a ring that I must use
In dear employment.
The ring is therefore not real, but merely a smokescreen to try and disguise his true intentions from his servant. The truth of this is further established in the following lines where Romeo in a rather frenzied fashion promises to "tear thee joint from joint" if Balthasar does not go. This is hardly the promise of a reasoning individual, and indicates that Romeo has some darker purpose, as Balthasar successfully intuits. Romeo is playing to an audience here, and trying to prevent Balthasar from either alerting anybody to his plans or stopping him from killing himself.