A few things can cause this, but your example settings point to two likely issues:

1. Diffraction at f/13: On a Canon 60D, f/13 is small enough to reduce sharpness due to diffraction. That can make detail look softer or slightly “glowy.” Try using a wider aperture such as around f/5.6 to f/8 if depth of field allows.

2. Noise / grain: ISO 320 is not very high, but lower ISO will usually look cleaner. Since your subject is stationary and you’re using a tripod and remote shutter, you can usually lower ISO and let the shutter speed get longer.

Also check these basics:

• Use the camera’s highest image quality setting.
• Make sure nothing is moving during the exposure.
• If you were handholding in other shots, slight movement could add blur that looks like glow.

So, for cleaner and sharper product shots: use the lowest practical ISO, avoid very small apertures like f/13 unless you truly need the extra depth of field, and keep the camera and subject steady.