Antedating of "off-colour"

[Hugo]

"off-colour", of diamond-mining (OED sense 1: 1860)

The Mirror of Literature, Amusement, and Instruction - Volume 5 - Page 15 - John Timbs - 1825:

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The smallest flaw, or foul (as it is called) greatly diminishes the price of the diamond; and if it be tinged with yellow, brown, &c., a fault characterised by the technical term off colour, its value falls very considerably, and is frequently reduced from a third to one half.
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http://books.google.co.uk/books?id=tBc4AAAAYAAJ&pg=PA15&dq=%22off%20colour%22%20OR%20%22off%20color%22&hl=en&sa=X&ei=uvWwUcSAJIuw4QTJoICQDw&redir_esc=y#v=onepage&q=%22off%20colour%22%20OR%20%22off%20color%22&f=false

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"off-colour", not in good health (OED sense 2b: 1876)
"off-colour", of questionable taste (OED sense 3: 1875)

I'm not sure if this next one is sense 2b or 3, but I guess 2b and it antedates both:

Paris in '67: Or, The Great Exposition, Its Side-shows and Excursions - Page 87 - Henry Morford - 1867:

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... and yet, though I have no doubt that the lady has been a little 'off color,' and though Mazeppa and the French Spy may not be exactly the thing in which we should like our sisters to 'show themselves' — yet, do you know, I am not only in love, ...
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http://books.google.co.uk/books?id=lbsDAAAAYAAJ&pg=PA87&dq=%22off%20colour%22%20OR%20%22off%20color%22&hl=en&sa=X&ei=efawUayFPJTZ4QS1zYCgDg&redir_esc=y#v=onepage&q=%22off%20color%22&f=false

Hugo

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