Dear Brian,

Thank you for your request. Thank you for the additional images and your patience. The presented object is a pair of columns with the measurements of 43 inches height. The columns are made out of a greenish-yellowish onyx or onyx opal. The use of this stone was common especially in the late 19th century and early 20th century. These columns were used as a base or stand for sculptures like busts. There are still many of comparable pieces offered on the auction art market.
This piece is in good condition and there are no serious damages visible.
An estimation would be between 1000 to 2000 USD.
This estimation is based on actual recent past recorded auction sales of comparables. Retail "asking prices" can be higher and vary.

With best regards,
Georg