Mila Kunis thinks people should think hard about whether they believe in a product before endorsing it.
The actress was announced as the new Global Brand Ambassador of Gemfields last month.
Mila wasn't looking for a new campaign when she was approached by the gemstone specialists, but agreed to commit after "falling in love" with the company.
"There's a difference being part of a family-owned company and being part of a conglomerate - you feel as though you're a part of something, and you don't work for them, you work with them," she told Vogue.co.uk. "You don't want to endorse something that you don't believe in. I've done that before and it's just one of the hardest jobs to do. Why do it? I believe in this company and I believe in what they stand for. Lesson learned, absolutely."
Mila has previously appeared in high profile shoots for the likes of Gap and Christian Dior, although she didn't expand on the work she didn't like so much.
She enjoyed working with a tight-knit company like Gemfields as she felt totally involved with the process.
"Pressure gets taken off you if they trust you and you trust them - then you're able to play around a bit and have some fun. I think pressure gets put on when there's a nervousness about where you stand and what you do and who's the boss," she continued. "That's when things become a little uneven. I think when you have the same goal, you want to achieve it and make each other proud and happy."
Mila made sure the London-based precious gem experts were an ethically inclined company before she agreed the deal. As part of her research, Mila travelled to Africa to learn more about mining practises and to take part in various community projects sponsored by the brand.
"That was absolutely the most important thing. Anything that has to do with stones I think you want to be a little cautious about," she admitted. "They opened their doors wide and just said, 'Go ahead'. It was great. They've been so great at letting me be a part of anything and everything I've been able to. I chose them in the same way that they chose me and I have honestly never worked for a better company."
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