Bests & Worsts Reviews from Amazon

I'm pretty sure this product is a knock off. This is the first time I have purchased anywhere besides the website and I noticed a big difference in the product. First of all, I got an email from the seller after purchase stating that the date on the tube is not an expiration date but a manufacture date. I thought that was kind of odd since the ones I have purchased off the website had a date on the bottom of the tube that clearly said expire date. This one said manufacture date and it was a past date. After using it for a week I noticed major build up on my lash line. Something that I did not get with the others. After a month of use I did not notice any different in my lash growth. Again, very different than the serum I have used before purchased directly from the website. I stopped using the serum I purchased here and ordered a new one from the website and what a difference. No build up and I can tell a difference in the my lashes after several weeks. I waited to post this review until I had several weeks of use to make sure my theory was correct. I wouldn't purchase this product from Amazon.