How we cite our quotes:
There lives or dies, true to King Richard's throne,
A loyal, just and upright gentleman. (1.3.2)
Mowbray shows up to the trial by combat ready to fight Henry Bolingbroke. His opening speech is actually less about what Bolingbroke charged him with than it is about affirming his honor and his loyalty to Richard. This is an interesting move: it shows that he has a grip on the real terms of the duel and knows exactly what this fight is really about – whether the king has the right to kill noble subjects and still expect loyalty, and what honor means when the king has started behaving illegally.
A jewel in a ten-times-barr'd-up chest
Is a bold spirit in a loyal breast. (1.1.6)
Mowbray is certainly interested in defending his good name here, but he's also reminding Richard of his value. Mowbray, who really does remain loyal to Richard, is a jewel. The metaphor can stretch even further, because Mowbray could also be the vault or chest keeping the jewel safe. The image of a jewel safely locked up in a chest is a clever way for Mowbray to tell Richard, albeit in code, that his secret is safe.
A dearer merit, not so deep a maim
As to be cast forth in the common air,
Have I deserved at your highness' hands. (1.3.3)
Mowbray, who has remained crazy-loyal to Richard and has covered up his participation in Gloucester's murder, laments the king's lack of loyalty to him. In return for his service, he is banished. Here he lets Richard know how he feels, but Richard, who has an underdeveloped sense of loyalty throughout the play, doesn't seem to pay much attention.