1 You can only get it later
The second stone and metal object can only be found later in the game after you leave the mansion. It is formed of two different parts that can be found in two different locations.
2 Find the jewelry box
Later on, after you leave the mansion and reach the tunnels you will come across a room in the tunnels where you will find a jewelry box.
3 Examine the jewelry box
Examine the jewelry box to find the first part of the stone and metal object which is the metal frame.
4 Go back to the mansion
To get the other part of the stone and metal object, which is the stone part, you need to get back to the mansion.
5 Get the emblem key
The emblem key will allow you to access the room that has the Spencer Emblem and this is where the other part of the stone and metal object can be found.
6 Go to the Spencer's room
Go the room that has the Spencer emblem and use the Emblem key to open it.
7 Turn the light on
The room will be dark and you will have to turn the light on to see the objects inside the room.
8 Combine both objects
In that room you will find the other part of the stone and metal object. Now you need to combine both parts to get the second stone and metal object.