UPDATED 5.31PM: New Zealand shotputter Valerie Adams has missed out on Olympic gold.

The Kiwi has finished with a silver medal in the women's shotput final in Rio, losing to American Michelle Carter who won gold with her final throw.

Adams was leading for much of the event after throwing 20.42 metres in her second attempt, but Carter threw 20.63 with Adams unable to answer with her final effort.

Hungary's Anita Marton was a distant third after a 19.87m effort.

After enduring a year of frustration and pain, struggling earlier in the year to regain her form after she had multiple operations, Adams said she's pleased with a silver.

"It's been a very long year for me and to even make it here and even be in contention, it's something I'm very proud of. It hasn't been easy but that's sport. We've got to take it and enjoy the moment."

Adams' coach Jean-Pierre Egger is very proud of Adams' success despite her not winning three Olympic golds in a row.

Egger was unable to travel to Rio due to a knee injury so he watched it play out on TV from Switzerland.

He said he plans to talk to Adams tomorrow and will tell her to celebrate her silver, especially after recovering from injuries over the past two years.

"Try now to keep her golden goals for her life, her projects she has with her husband. I think this is the most important now."

Egger said Michelle Carter was not seen as a threat by Adams in the lead up to the competition.

He said China's Gong Lijiao and especially Germany's Christina Schwanitz were discussed as her likely tough competition.

"I heard she said she will throw 21 in this competition, but she was so far from such a result."

The Beijing and London Games champion was vying to become the first New Zealander and first female track and field athlete to win back to back to back Olympic gold medals.

Adams' silver is New Zealand's sixth of the Games, with our current total seven after seven days.

Adams will now also feature on a new stamp which celebrates her success at the Rio Games.

New Zealand Post's Head of Stamps and Coins Simon Allison said they are very proud of her achievements in Rio.  

“Featuring Valerie on a stamp is all the more special to us because she is a New Zealand Post ambassador and has represented us at so many junior sport and community events. 

“Our athletes are inspirational and like the rest of New Zealand, we will continue to follow their progress in Rio,” said Mr Allison.

The stamps are available to order online at nzpost.co.nz/roadtorio and a range of Olympic medallist stamps will be available for purchase in selected PostShops.