This picture shows you a seedling which is a pure chinese type--Engineer-Shortleaf.
Now, its leaves are still thin and long.
The width of the leaves of an adult pure chinese clivia plant's will be 7~13cm. But will differ from different types. Some types will reach a width of about 10~13 or even more, such as Roundtip, Monk, etc. the others will be not as wide as these types, they will reach a width of 7~10cm, such as Painter, Shortleaf, etc. If you keep fertilizing the plants with nitrogenous fertilizer reasonably, you will probably get perfectly broad leaves. I think the bone dust is a very good organic nutrition for clivias. I am used to use this kind of fertilizer as well as stir-fried seeds of oil plants. You can have a test with them.
This picture shows you an adult plant of which the type is also Engineer-Shortleaf.
Now, in a certain, you can find the changes of the leaves from these 2 pictures.