If you don't find what you need on our site, please contact us so we can assist you. Starbucks Online Store Customer Service Team. Customer Service Team hours are Monday through Friday, 5:30 a.m. - 5:00 p.m. PT, Saturday, 7:00am - 3:30pm PT, Sunday, closed. Call us toll-free at 1-877-421-9062. Contact the Starbucks Online Store Customer Service Team via e-mail using the form below:
The smallest particle visible to the naked eye is 40 microns. To give you some perspective, a piece of hair's width can range from 40 to 120 microns.
Experts believe that the naked eye â a normal eye with regular vision and unaided by any other tools â can see objects as small as about 0.1 millimeters. To put this in perspective, the tiniest things a human being can usually see with the naked eye are things like human hair (with the naked eye and under a microscope) and lice (with the naked eye and under a microscope). With the help of powerful microscopes, though, humans are able to see incredibly small things impossible to see with the naked eye.