Green’s Dictionary of Slang

1. a counterfeit coin.

1839		H. Brandon ‘Dict. Flash or Cant Lang.’ in ‘Ducange Anglicus’ Vulgar Tongue (1857).
1857		‘Ducange Anglicus’ Vulgar Tongue.
1864, 1867, 1870		Hotten Sl. Dict.
1882		Sydney Sl. Dict. (2 edn) 8: Sheen - Bad money.
1888		J. Payn Eavesdropper II ii n.p.: ‘Can you smash a thick ’un for me?’ inquired one, handing his friend a sovereign. ‘You’re sure it ain’t sheen?’ returned the other, with a diabolical grin [F&H].
1895		C. Crowe Aus. Sl. Dict. 72: Sheen, bad money.
1901		Argus (Melbourne) 20 Sept. 6/4: Counterfeit [money] is sheen or kone or sinker or any other inexplicable and contemptuous term.
1935		R.T. Hopkins Life and Death at the Old Bailey 63: The following crook’s words and phrases date from the days of the old Old Bailey: [...] bad money – sheen or sinker.
1999		(ref. to late 19C) G. Seal Lingo 147: sheen meant bad, probably counterfeit, money.

2. (Aus.) money.

1882		Sydney Sl. Dict. 9/2: Kino, the macing cove, kidded on a dollymop where the bloak’s got a swag of sheen. Kino’s cocum, and he’s stagging to crack the crib. Kino, the housebreaker, enticed a servant-girl (to keep his company) where the master has a quantity of plate. Kino’s wary, and he is watching to break into the house.
1941		Baker Popular Dict. Aus. Sl.
1955		N. Pulliam I Travelled a Lonely Land (1957) 238/2: sheen – money.