You will need to send both for a full calibration. The gloss meter must be used with a certified standard for traceable results. It has its linearity tested against NIST standards. The tile has a value assigned. When the instrument is calibrated on the provided tile, the results are traceable to our NIST certification in accordance with BS EN ISO 2813, which is the main standard for the measurement of gloss.
We do have a tile-only calibration option however, we would recommend that this is used only for additional tiles.