What is most natural breast augmentation to get it as big as this? (photo)

hello thank you for your question and provided information as well. based on the photo shown, the ideal would be to be consulted in person by a certified plastic surgeon who sees your case and gives you the guidelines and guidelines of which techniques would be ideal for the result you want?

An implant will augment the breast you naturally have. Putting a large implant into a smaller breast won't necessarily achieve the same result as augmentation of a larger more ptotic breast.

Patients often think in terms of cup size when considering augmentation. Unfortunately, devices are sized in terms of milliliters (cc) of volume. This can lead to some confusion when sizing. Additionally, it is important to remember that cup size itself is not standardized with variations from one manufacturer to another. Unfortunately, as many women can attest their cup size in an industry leader such as VS is not necessarily transferable to another brand.
Another point which is often under appreciated is that of anatomy and starting point. Any implant will add volume to the volume which is already present. The implant is additive. A particular volume will not necessarily confer the same cup size to different patients (often times it will not even confer the same cup size to different breasts in the same individual...remember they are "sisters" not "twins"). 
A general rule of thumb is that 125cc can represent somewhere between 1/2 to a full cup size increase. Smaller volume differentials (25-50cc) are typically less consequential representing a volume change of less than a shot glass. However, I have found these numbers, at least anecdotally, to be of little help. Patients often present with notions/goals which do not correlate with these sorts of sterile volumetric assessments.
When sizing patients, there are a number of useful tools including:
-3D imaging (has the added benefit of offering a volumetric analysis of the pre-operative breast)
-Breast sizers (rice bags)
-Goal photos
I also recommend that patients commit to a particular look rather than a cup size. Once a patient settles on a look that pleases them the overall cup size increase becomes less relevant.The key to obtaining a natural result is to stay within the parameters defined by your BWD. This will ensure that you avoid the dreaded "fake" look. It is also important to define "natural" for your surgeon as most assume this to mean an matching size to frame. Small patients tend to have small breasts and vice versa. Smaller framed individuals will oversized implants do not tend to appear "natural." A good rule of thumb is the bigger = faker.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).