"In the midnight sun, it will look like a large diamond," said Magnus Bredeli Tveiten, project manager at the Directorate of Public Construction and Property.
In winter, when the sun does not rise above the horizon, "it will glow into the darkness," he said.
'Millions' of seeds
Situated about 130 metres above current sea level in the Norway's Svalbard archipelago, the complex will not be affected if Greenland's ice sheet melts - which could increase sea levels by seven metres.
It will expected to be safe from flooding even if all of Antarctica's ice melts, which experts say could increase sea levels by up to 61 metres.
Tveiten said: "We have taken into consideration the [outside] temperature rising and have located the facility so far inside the rock that it will be in permafrost and won't be affected."
Three million batches of seeds from all known crop varieties will be stored at sub-zero temperatures inside two large chambers, accessed by a tunnel with an airlock.
The entrance to the vault, dubbed the "Noah's Ark of food", will be illuminated with artwork that changes according to the light.
Construction on the $3m seed bank will begin in March. It is expected to open in 2008.