The candleholder on the left is Diamond and on the right the candleholder is Central. Only Diamond and Central made the 9 inch size in this style.
The easiest way to tell them apart is in the top rim. The top rim of the Central has a small amount of additional glass on it and the mold marks are polished out. The Diamond candleholder rim is not flat and the mold mark is obvious.
Another difference is that the second shoulder ring is straight on the Central candle while the Diamond one is rounded out.
The base on the Central candle is rounded and no seams are present while the Diamond base is straight sided.
