I'm trying to find out whether is my gucci watch original or a copy. Is there a model with the code 705196-15?

SOURCE: How do I open my gucci watch to change batteries?

Get a #0 1.6mm precision Phillps screwdriver (these are brittle) or similarly strong, thin piece of steel.

Hold the watch upside-down across your index finger while gripping the straps tightly between your index finger and thumb on one side, and index finger and middle finger on the other (ie. squeeze the strap around your index finger).

On the underside of the watch, stick the tip of the screwdriver under a square slot where the watchband is connected at an angle perpendicular to the strap. Firmly pry upwards on the cover on one side, then the other, until the cover pops off.

The battery is a Renata 379.

To put the cover back on, align the square slots precisely with the ends of the straps (keep these out straight), then firmly push the cover straight down until it "snaps" shut.

SOURCE: How to Open a Gucci watch

Most watches are either screwed on and typically have a series of small notches around the circumference of the case back. A special tool is generally called for. Otherwise they are "snap back" . These are simply pressed on. To remove you can carefully use a regular knife in the absence of a "case knife". There is usually a small gap/groove/notch area to insert the balde and lift the back off.