why does replacing integer values with arabic numbers give me different results Gridview

I had a table field named 'topicfull' code. Its type was varchar(50). I had some values as follows

Now I want to change the value of topicFullCode into arabic numbers. So I have changed the type of the table name using the following query.

ALTER TABLE TopicInfo 
ALTER COLUMN topicFullCode NVARCHAR(50) null 

Then create a function as follows:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE FUNCTION [dbo].[ReplaceIntegersWithArabicNumbers]
(
@str NVARCHAR(1000)
)
RETURNS NVARCHAR(2000)
AS BEGIN

DECLARE @newStr NVARCHAR(1000)
set  @newStr= ''
declare @val NVARCHAR(1)
set @val = ''
declare @i INT
set @i = 1

    WHILE @i<=LEN(@str)
    BEGIN
        SET @val = SUBSTRING(@str, @i, 1)
        IF ((@val) >= '0' and (@val) <= '9')    
        BEGIN
            SET @val = 
                CASE @val
                    WHEN 1 THEN N'۱'
                    WHEN 2 THEN N'۲'
                    WHEN 3 THEN N'۳'
                    WHEN 4 THEN N'٤'
                    WHEN 5 THEN N'۵'
                    WHEN 6 THEN N'٦'
                    WHEN 7 THEN N'۷'
                    WHEN 8 THEN N'۸'
                    WHEN 9 THEN N'۹'
                    WHEN 0 THEN N'۰'
                END -- CASE
        END -- IF
        SET @newStr = (@newStr + @val)

        SET @i=@i+1
    END -- WHILE
RETURN @newStr
END

And execute the following query to replace the values.

UPDATE TopicInfo
SET topicFullCode = dbo.ReplaceIntegersWithArabicNumbers(topicFullCode)

It shows the following results from the SQL Server 2005 query window.

But when I show this data in Gridview the decimal point seems like comma (,) as shown in the following figure.

I need to know why this is happening and a solution of it.