It would have much amazed you.
Very like, very like. Stay'd it long?
While one with moderate haste might tell a hundred.
MARCELLUS & BERNARDO
Not when I saw't.
His beard was grizzled, no?
It was, as I have seen it in his life,
A sable silver'd.
I will watch to-night;
Perchance 'twill walk again.
I warrant it will.
If it assume my noble father's person,
I'll speak to it, though hell itself should gape
And bid me hold my peace. I pray you all,
If you have hitherto conceal'd this sight,
Let it be tenable in your silence still;
And whatsoever else shall hap to-night,
Give it an understanding, but no tongue:
I will requite your loves. So, fare you well:
Upon the platform, 'twixt eleven and twelve,
I'll visit you.
Our duty to your honour.
Your loves, as mine to you: farewell.
Exeunt all but HAMLET
My father's spirit in arms! all is not well;
I doubt some foul play: would the night were come!
Till then sit still, my soul: foul deeds will rise,
Though all the earth o'erwhelm them, to men's eyes.
The hellmouth was frequently a spectacular scenic effect in medieval dramas and pageants. Sometimes it was elaborately constructed and had its own wagon - as in the illustration here. Hamlet (or at very least Shakespeare) doubtless saw some kind of performance featuring such an effect, and it's likely he has it in mind in his theatrical speech in this week's segment of the text.
SABLE AND SILVER
As mentioned in the episode, there are heraldic connotations to sable as a colour. As well as being a rather luxurious (and warm) fur, to which Hamlet himself will make reference later in the play, there's a long tradition of sable being a colour used in heraldry. Shakespeare had already linked the two in his twelfth sonnet:
When I do count the clock that tells the time,
And see the brave day sunk in hideous night;
When I behold the violet past prime,
And sable curls all silver'd o'er with white;
When lofty trees I see barren of leaves
Which erst from heat did canopy the herd,
And summer's green all girded up in sheaves
Borne on the bier with white and bristly beard,
Then of thy beauty do I question make,
That thou among the wastes of time must go,
Since sweets and beauties do themselves forsake
And die as fast as they see others grow;
And nothing 'gainst Time's scythe can make defence
Save breed, to brave him when he takes thee hence.
Sable shows up in several royal coats of arms throughout Europe, and is often matched with argent, or silver. Shakespeare's own coat of arms is described thus, in a draft from October 1596:
The arms are blazoned. “Gold, on a bend sable, a spear of the first, steeled argent [a gold spear tipped with silver on a black diagonal bar]; and for his crest, or cognizaunce a falcon his wings displayed argent, standing on a wreath of his colours, and supporting a spear gold steeled as aforesaid, set upon a helmet with mantles and tassels as hath been accustomed”
So, it looked something like this: