I am 5"7 155lbs. Will 850cc look good on me? (Photo)

850cc breast implants are discouraged in my practice. Large implants such as these may look great the first couple of years but after that can greatly stretch your tissues requiring a lift or revision in the near future. Not to mention chronic pain, capsular contracture, implant displacement, bottoming out, etc. I highly recommend you visit the breast implant revision forum and educate yourself about the complications associated with having large breast implants. Best wishes, Gary Horndeski M.D.

Thank you for the question. Ultimately, careful measurements (dimensional planning) will be an important part of the preoperative and intraoperative planning process. Breast lifting will not be necessary.       Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery ( regarding breast implant size/profile selection) is:
 1. Concentrate on choosing your plastic surgeon carefully.  Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your   desired goals  with your plastic surgeon. This communication will be critical in determining which operation and/or breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "C or D cup" etc or "look awesome” means different things to different people and therefore prove unhelpful.
 Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup  size may also be inaccurate.  The use of  in bra sizers and computer imaging may be very helpful during this communication phase.
3.  Once you feel you have communicated your goals clearly,  allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals.  Again, in my practice, this decision is usually made during surgery.  I find that the use of temporary  intraoperative sizers ( with the patient in the upright position)  allows for accurate selection of breast implant size/profile to achieve patient's goals as precisely as possible.
I hope this, and the attached link (dedicated to larger breast augmentation outcomes), helps.

It is difficult to assess your situation based on the limited picture you provided but I would think that an 850 cc implant will be too large for your breast.