YUDIbt

Today I am going to present a tutorial on modelling diamond using 3D Max. Though it is having a simple and symmetrical object, it is not straight forward to model using the basic objects available with 3D Max. From this tutorial I will guide you to model a diamond within few minutes time, surely within one hour if you having the basics.
Though, just said the diamond shape there are number of shapes use for diamond cutting. Among them, I have selected “Round brilliant” shape for this tutorial since it is one of the most common shape.
To start modelling, create a “Hedra” object (Create > Geometry > Extended Primitives > Object Type rollout > Hedra) with default parameters. You may change the size of the object by changing Radius as you like.


Place the create object at the origin (0, 0, 0) using “Move Transform Type-In” (you can get it by right-click on “Select and Move” toggle). Then right-click on the object and convert it to an “Editable Poly”.
Go to “Edge” Sub-object level, select top 4 edges and connect them with a new ring of edges at the centres using “Connect” tool available under “Edit Edges” rollout.

Go to “Polygon” ” Sub-object level, select the 4 polygons above the newly added edge ring and delete them.

Now it is need to close the opening of the object which is created after deleting the polygons. To do that, go to “Border” Sub-object level, select the border of the opening and press “Cap” button available under “Edit Borders” rollout.

Turn on Snap, and draw a NGon (Create > Shapes > Splines > Object Type rollout > NGon) across the top 4 vertices with 8 sides. So, 4 out of 8 points of your NGon should go through top 4 vertices of the object.

Go to “Edge” Sub-object level and select one of the 4 edges of the top square shape and the parallel edge in the next level: all together 2 edges (see figure below).

Connect the selected 2 edges using “Connect” tool available under “Edit Edges” rollout. Repeat these steps to other 3 sides of the top square. After repeating, you should have something like below.

Go back to Vertex Sub-object level and move the 4 remaining top vertices (newly added) on to the remaining edges of the nGon keeping Snap on.

Draw 4 new lines connecting the bottom-most vertex and the 4 newly added vertices in the mid raw using “Cut” tool available under “Edit Geometry” rollout.

Draw another NGon with 8 sides across the 4 outer mid vertices as you done early.

Mover the 4 remaining vertices on to the vacant NGon points using Snap. Now you can see, you are having the basic shape of a diamond.

Now we are going to add more details to the diamond by further dividing the faces. To do that, select the 8 edges which are connecting top and mid rows and add another vertex ring between top and mid levels (near to top level) using “Connect” tool available under “Edit Edges”.

Select 8 new edges and 8 edges in the mid raw and connect them again using “Connect” tool. You should get something like below.

Then draw the following pattern by connecting the vertices of the top level and new vertex ring using “Cut” tool.

Again draw the following pattern by connecting the vertices of new vertex ring with the mid level vertices using “Cut” tool.

Remove the vertices marked in the above image.

Now change the positions of the top vertex ring and newly added vertex ring by move them along Z-axis and scaling until you get a proper shape like below.

Now, top section is complete and we can move to the bottom.
Select the lone 8 edges in the bottom section and draw a new line connecting them in the mid-height using “Connect” tool.

Then draw the following pattern using “Cut” tool.

After drawing the pattern, we do not need the edge ring we added to the bottom section anymore. Go to Edge Sub-object level and remove them.

Now go to “Vertex” Sub-object level, select the bottom most vertex and Chamfer it by small amount.

Now it is almost complete, but there are few more things to do to make it perfect.
Draw another NGon with 8 sides across the mid level vertices if you already deleted the one you drawn early. Or you can use the previous NGon if it is still there. Select the NGon and Increase the number or sides to 16. Select the diamond object, go to Vertex Sub-Object level and move the remaind 8 vertices in the mid level to vacant NGon points.

Select the NGon and increase the number of sides to 64 and decrease the radius of the NGon to make it just inside the diamond.

Apply Extrude modifier to NGon with an Amount higher than the height of the diamond. Move it along Z-axis to cover the diamond as you see below.

Apply Boolean operation to the objects as an “Intersection”. As a result, It will give you the diamond shape you had early with a belt around it.

However, sometimes it will remove some of the edges of the object. If so mark them again using “Cut” tool.
After correcting the minor errors you can get the final object. This is what I got.