It is one of the higher grades of wood in the stock and forearm.
Your Browning lightning superposed shotgun was made in the year 1968 with the serial number that you have provided.
Around $5000.
Browning can tell you how it left the factory, and the gun can be dated by serial number.
100-10000 usd
Depending on condition, a few hundred to a few thousand USD.
100-1000 USD or so depending on specifics
A lot!. Starting with the least expensive, Grade 1, Pigeon, Diana and Midas. After WWII, Grade 1 Grade II, Grade III, Grade IV, Grade V, Grade VI. In 1960 they started back with Gr 1, Then Pigeon, Pointer, Diana and Midas. Presentation grades were 1,2,3&4. Waterfowl limited edtions were Mallard, Pintail, Black Duck and Bicentennial.
100-1000 USD or more depending on specifics
The value of a 12 gauge Browning Citori Pigeon Grade is actually dependent upon a number of factors. Some of these factors would be the age and condition.
Only Browning knows. Information not in the public domain.
Impossible to tell without pictures.
I f you have a grade I superposed skeet? then it is going for 700 dollars if in 60% condition to 1200 dollars for one in 90% condition.If your browning is in 20ga. then you could add anywhere from 100-700 dollars depending on the amount of original finish left.