Physical meaning not synthetic (eg not options or futures).
but still not very transparent, with no proof to show orders are actually pegged against provable fait.
If you go to the minute charts you will see that stamp invariably lags bitfinex. I tend to agree with Hairy, of all the exchanges I have ever dealt with from mtgox through stamp, finex, the old gdax, coinfloor and now binance , stamp are the exchange that have generally felt the least bullshitty.