The Bluenose is pictured on the starboard tack, elegantly riding a brilliant froth of waves as it manoeuvres out to sea. But what really catches the eye is not the famous schooner – it’s the sky behind it. Instead of a pale metallic sheen, that portion of the collector’s coin is coloured like a vivid sunset that transitions from golden pink near the horizon to a deep blue by the time it reaches the top of the ship’s main mast.
Amazingly, the effect was achieved without the use of dyes, inks or pigments.
“It’s just pure silver,” Iain Brooks, senior manager of applied research at the Royal Canadian Mint in Ottawa said as he cradled the hefty, five-kilogram coin with two hands.
The coin is both an art piece and a test of a surprising new technique dubbed “plasmonic colouring” that was developed by the Mint together with researchers at the University of Ottawa. It was created with the help of a picosecond laser, which can blast its target with precise, high-energy pulses of infrared light that last only one trillionth of a second. Researchers have discovered that by applying the pulses in just the right way, they can microscopically tailor a coin’s metallic surface so that it transmits only certain wavelengths of light while absorbing others. In essence, instead of colouring a coin, the technique allows a coin to colour the light it reflects.
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Well now isn’t this the greatest thing for Canadian coins. Too bad Canada doesn’t have any gold reserves.