Keep going straight, then there is a little plate with four lines, get all the lines to match up horizontally then jump on them and then you'll find a new room with a blocked passage. The the cubes to line up correctly with the figure on the wall, and the passage will open.
The tomb is inside the Sphinx at Giza, on Nabooti Island. (see related question)
You have to get past the tomb robbers and enter the tomb under the Sphinx, where you will find the Blue Jewel. (see the related questions)
its in the tomb in giza.
Once you get the blue flower at Nile Falls, you can bring it to Nabooti island and trade it for a black turban. Then fly to Giza and put on the turban, the tomb robbers will think you are one of them and give you a shovel.
It is the final challenge in the tomb under the Sphinx on Nabooti island. (for the solution, see the related question)
The Sphinx is at Giza on Nabooti Island (Egypt is in north Africa). The blue jewel is in the tomb beneath the Sphinx.
Vince is Vince Graves, fortune hunter and tomb robber. He is looting the tomb of the Sphinx at Giza on Nabooti Island. He has the Moonstone in his bag, and if you get it, you can open the Sphinx. (see related question)
Use the Moonstone to enter the Sphinx, and solve the three challenges there. The Blue Jewel is in the Sphinx.(see the related question)
The Sphinx at Giza has four challenges to defeat in order to get the Green Jewel. To enter the tomb, or solve the challenges, see the related questions.
No cowboys on Nabooti Island. The masked men at Giza are tomb robbers. Get the blue lily from Blue Nile falls and swap it for a turban at Nabooti. Wear it when you go to Giza.
The blue jewel for Nabooti is in the tomb inside the Sphinx at Giza. (see related question for solution)
the blue gem is at giza.you go to where the tomb is.when you are finished with that the tomb will open.