Winery staff line a conveyor belt and watch the premium berries go by, carefully checking for any imperfections.
They believe each berry is important to the quality of the wine, and are quick to remove any that don't make the grade.
Boutique wineries Dog Point Vineyards and Te Whare Ra are among the wineries in Marlborough which hand-sort their grapes.
Te Whare Ra owner Anna Flowerday said they began their harvest on Monday by hand-picking gewurztraminer for their Toru blend. The fruit came from their 16-year-old vines, she said.
"Because we hand-pick all our fruit, we hand-sort it all as well. We do that for quality reasons and quality control.
"It is really important. It makes a significant difference in the wines in the end."
Mrs Flowerday said they sort their pinot noir by hand - twice. They hand sort their other varieties once.
The hand-sorting was an "attention to detail" thing, Mrs Flowerday said.
"It's a bit obsessive compulsive but there is a lot of investment that goes into the sorting.
"Pinot noir needs the extra attention."
Dog Point Vineyards began their harvesting season by hand-picking pinot noir on the last day of summer, February 28.
They were hand-sorting whole bunches of the variety when the Express visited on Tuesday.
"We are looking for everything that is not quite right, not quite ripe enough just anything that is not making it a perfect bunch, we chuck," winemaker Murray Cook said.
Owner Ivan Sutherland said they have picked half their pinot noir already.
Mr Sutherland said once the whole bunches were sorted they would go into a tank with the de-stemmed berries.
Whole bunches account for 10 per cent of the pinot noir blend, and individual berries the other 90 per cent.
"We are looking for a bit of secondary flavours . . . to give it a whole other dimension.
"It makes the wine taste a little more lifted."
- The Marlborough Express