Why does Mr Merdle ask for a penknife with a darker handle in "Little Dorrit"?

Question

In Chapter 24 of Little Dorrit, in one of the last scenes, Mr Merdle asks for a penknife. When Mrs Sparkler hands him the knife he asks if he could have one with a "darker" handle.

‘So I am off,’ added Mr Merdle, getting up. ‘Could you lend me a penknife?’

It was an odd thing, Fanny smilingly observed, for her who could seldom prevail upon herself even to write a letter, to lend to a man of such vast business as Mr Merdle. ‘Isn’t it?’ Mr Merdle acquiesced; ‘but I want one; and I know you have got several little wedding keepsakes about, with scissors and tweezers and such things in them. You shall have it back to-morrow.’

‘Edmund,’ said Mrs Sparkler, ‘open (now, very carefully, I beg and beseech, for you are so very awkward) the mother of pearl box on my little table there, and give Mr Merdle the mother of pearl penknife.’

‘Thank you,’ said Mr Merdle; ‘but if you have got one with a darker handle, I think I should prefer one with a darker handle.’

‘Tortoise-shell?’

‘Thank you,’ said Mr Merdle; ‘yes. I think I should prefer tortoise-shell.’

Shortly afterwards (chapter 25), we see the scene where he has killed himself in the bathtub.

There was a bath in that corner, from which the water had been hastily drained off. Lying in it, as in a grave or sarcophagus, with a hurried drapery of sheet and blanket thrown across it, was the body of a heavily-made man, with an obtuse head, and coarse, mean, common features. A sky-light had been opened to release the steam with which the room had been filled; but it hung, condensed into water-drops, heavily upon the walls, and heavily upon the face and figure in the bath. The room was still hot, and the marble of the bath still warm; but the face and figure were clammy to the touch. The white marble at the bottom of the bath was veined with a dreadful red. On the ledge at the side, were an empty laudanum-bottle and a tortoise-shell handled penknife—soiled, but not with ink.

My question is: why did Mr Merdle ask for a penknife with a darker handle?

(Reposted from here as a commenter suggested.)

Answer 1

A man may have a fancy as to the particulars of how he takes his own life, but here are a couple of things which may have informed his choice.

He may have found the shimmering, iridescent paleness of Mother of Pearl to have some heavenly quality which would make it a more jarring tool for the commission of an act of suicide, considered at that time to be a blasphemous act or a mortal sin.

Such a view may be reinforced by consideration of the Bible verse Matthew 7:6

Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.

When he is given the tortoiseshell knife Mrs Sparkler says

'I will forgive you, if you ink it.'

Which suggests that the staining of pen knife handles with ink is not uncommon.

'I'll undertake not to ink it,' said Mr Merdle.

As your own later quote makes clear, he does stain the knife, though with his blood rather than with ink. So it is possible that he was considering that blood might stain the handle of the Mother of Pearl knife, which was - after all - only on loan.