Colour is very difficult to judge from a photo, but the decanter Thomas first asked about doesn't look like Whitefriars Sea Green to me. It looks more like WF Emerald or Early Sky Blue - the two colours can be difficult to tell apart when the glass is thin. I'm going by the colour in the knop, where it's thickest, and it looks too blue-y to me to be WF Sea.
Beautiful piece, whatever the colour!