Lewin says the assistant told her she had to pay for her Meadowlark ring first and asked Lewin to provide ID before showing her a large diamond ring valued at about $10,000.
But when Lewin asked for a closer look, she says the assistant pulled the ring out and put it on her own finger. She then held it up to her chest to show her.
"I was like I would like to try the ring on and she said, 'Well you can't, it's store policy. Any high-end rings can't be tried on'."
Lewin then turned to another assistant to ask if it was correct, who responded "sometimes".
Lewin said she finally clicked what was happening when she spotted a security guard standing by the door looking at her.
"I think she thought I was going to do a runner - seriously."
She asked to speak to a store manager but was told there was not one on site that Saturday. As she went to leave she turned to the assistant and said, "It's not because I'm a Maori is it?".
She said the shop assistant stumbled and tripped over her words, before saying, "Oh, don't say that".
Lewin said she left the store feeling upset and returned on the Sunday to complain.
The store manager called Lewin on Monday morning to apologise and gave her the distinct impression it was not store policy.
"There's no reason - you've got the ID, I've paid for a $450 ring - why would she think I would run away with it."
Responding to the Herald's request for comment, Walker & Hall spokeswoman Liz Yarrell confirmed the store's management had investigated the incident.
"We consider the matter closed with the customer being satisfied to our knowledge at this time," she said.
Yarrell did not respond to requests for a clarification around the store's policy around trying on rings.
However, she said the assistant's claim it was store policy not to let customers try on high-end rings was incorrect.
Lewin also asked to speak with the owner but, after not hearing from him for two days, she went back into the store and returned her $450 ring.
"I thought hell no I'm not spending $450 in your store when you've treated me like that."
The store owner called her back as Lewin was on her way home from returning the ring to apologise. He also told her it was not how they wanted customers to feel.
"It didn't make me feel any better about the situation."
Lewin also contacted Walker & Hall's head office via Facebook who said a regional manager would be in touch but never was.
She later purchased the same $450 ring from another Walker & Hall store.
"Taika Waititi called it and, yeah, I was made to feel like a criminal basically because I'm Maori."
She said people were saying such things did not happen following Waititi's comments, but she and her husband, who had also been subjected to racism on numerous occasions, disagreed.
She and her husband were comfortable financially and could afford the ring, she said.
After the Herald contacted Walker & Hall for comment, the owner of the NorthWest franchise called Lewin back extremely apologetic. He offered to refund the $450 she had spent on the Meadowlark ring. She accepted the offer, which she thought was generous.
