Tatiana Fernandez lost the diamond band in a box of children's books during the packing process in Gourock, Inverclyde.
Unbeknown to them, it had been sent to a customer in Manchester.
She had unwittingly packed the ring in a customer's parcel
Stephenie Healiss got in touch with Amazon and Ms Fernandez was reunited with her precious possession.
She said: "When I realised I'd lost my engagement ring, I went through a range of emotions, from sadness to anger at myself for losing it. I honestly thought it had gone forever.
"When our leadership team got in touch to say a customer found it in their package, I couldn't believe my luck. It's such a relief to get my ring back and I'd like to say a heartfelt thank you to our kind customer for returning the ring to me."
But was stunned when the customer alerted Amazon and returned the diamond band
The couple, who met while working at Amazon's Gourock site near Glasgow, are currently planning their big day and will now marry with the original engagement ring thanks to the kindness of the customer.
Ms Healiss said: "I was surprised, yes. I could tell the ring had a great deal of sentimental value and know from my own experience that things like that cannot be replaced.
"That's when we decided to contact Amazon. I am so pleased it's been returned safely and wish Tatiana and Stuart all the very best for their wedding day."