Duh...I left out a semi-colon.

SELECT Customers.company, Inventory_in.chgperkt, Inventory_in.clarity,;
Inventory_in.colors, Inventory_in.cut, Inventory_in.entered,;
Inventory_in.invoiced, Inventory_in.removed, Inventory_in.inactive,;
Inventory_in.karatwt, Inventory_in.measure, Inventory_in.p_descript,;
Inventory_in.stocknum, Inventory_in.total_chg, Transactn.track_num,;
Transactn.transdesc;
FROM inventory!inventory_in ;
INNER JOIN inventory!transactn;
ON Inventory_in.trans_id = Transactn.trans_id;
INNER JOIN inventory!customers ;
ON Customers.cust_id = Transactn.cust_id ;
GROUP BY Customers.company;
ORDER BY Inventory_in.stocknum

>Is there some way to edit the SQL generated in the view designer?

No. You can programatically create views using your own syntax and force them into the DBC but I don't recommend it. If someone tries to edit the view using the view designer it may result in an error.